Optavia (now Trilivy)

Diet Reference Archive: a commercial program

Optavia (now Trilivy)

A commercial weight-loss program in which most meals are replaced by the company's packaged products, called Fuelings, with one or more self-made meals and support from an independent coach who sells the products. In July 2026 the company renamed it Trilivy and now markets it for what it calls metabolic health.

Family: Commercial programs and products Promoted by: Medifast, Inc., a publicly traded company, through independent coaches First appeared: 2016, as a product line of Medifast's coaching business; renamed Trilivy in July 2026 GRADE: Moderate for more body weight lost, as measured, at 16 weeks on the program as currently sold (the 5 & 1 plan with an independent coach) than on a self-directed reduced-calorie diet, in adults aged 18 to 65 with overweight or obesity and without medicated diabetes; this page's own judgment from one company-funded trial of the 2016 version

ON THIS PAGE

1. In brief
2. Overview
3. In practice
4. For the coach
5. The evidence (opens on request)
6. Mechanisms (opens on request)
7. Risks, contraindications and myths (opens on request)
8. Key terms
9. Review questions
10. References
11. Evidence rating and review record

The summary and sections 1 to 3 are the short version and are open when the page loads. Sections 4 to 6 hold the research detail, the biology, and the cautions. Each of those opens when you select its heading, and you can read the page without opening them. The program was renamed Trilivy in July 2026; this page uses the name most clients know and describes the program as the company's own pages described it on October 11, 2026. Back to the Diet Reference Archive index.

In brief

What is it? A commercial weight-loss program run by Medifast, Inc. A client buys the company's packaged meal replacements, called Fuelings, and on the main weight-loss plan eats 5 of them a day plus one self-made "Lean & Green" meal of lean protein and non-starchy vegetables, with support from an independent coach who is paid through the company's compensation plan (Medifast, Inc., 2026a; Trilivy, n.d.-j). In July 2026 the company changed the program's name from OPTAVIA to Trilivy (Medifast, Inc., 2026d).

Does it work? In the company's own 16-week trial, adults on the 5 & 1 plan with telephone coaching lost an average of 5.2 kilograms, against 0.2 kilograms for adults following a reduced-calorie diet on their own (Arterburn et al., 2019). Two older trials compared the same meal plan, sold without a coach, with food-based diets of similar calories: at 52 weeks the larger found more weight lost on the meal plan; at 40 weeks the smaller, reporting only those who stayed, showed no clear difference; both saw partial regain (Davis et al., 2010; Shikany et al., 2013). The searches for this page did not identify a trial that followed people on the coached program or the 5 & 1 plan past 1 year, one that measured heart attacks, strokes, cancer or deaths, or one that separated the effect of the coaching from the effect of the food plan.

Is it safe? In the company's 2019 trial, the side effects judged related to the diets were mild or moderate and mostly digestive (Arterburn et al., 2019). The company itself warns that rapid weight loss may cause gallstones, temporary hair thinning or muscle loss, and dizziness or tiredness while adjusting (Trilivy, n.d.-f). The main plan supplies about 800 to 1,000 calories a day (Arterburn et al., 2019), within the 800 to 1,200 calorie range that England's national clinical guideline calls a low-energy diet. That guideline advises such diets only within a specialist weight-management service with long-term support, nutritionally complete, supervised, for no more than 12 weeks, after a review of the person's medicines (National Institute for Health and Care Excellence, 2025). The company states that it does not use physicians or nurses to monitor its clients (Medifast, Inc., 2026a). The Very Low Calorie Diets page explains these terms.

Who should not do it without talking to a doctor or dietitian first? Anyone considering it, since the main plan is a low-energy diet; the company itself tells clients to consult a healthcare provider first (Trilivy, n.d.-f). Its disclaimer says not to use its plans while pregnant or under age 13; says the main plan is not appropriate for teenagers, nursing mothers, sedentary adults 65 and older, people with gout or type 1 diabetes, or people who exercise more than 45 minutes a day; and asks anyone with a serious illness or an eating disorder history to be cleared first (Trilivy, n.d.-f). Anyone taking insulin or another diabetes medicine, blood pressure medicine, a diuretic, warfarin, lithium or thyroid medicine keeps the prescriber informed before starting; the coach never changes a medicine. With kidney disease, the kidney care team is involved, since needs depend on stage, lab results and dialysis.

Related pages: Meal Replacement Programs, which covers the research on meal replacements as a category; Very Low Calorie Diets; WeightWatchers; and Noom. Full list on the archive index.

1. Overview

What you eat

The program sells several plans built from the same 2 parts: Fuelings, the company's name for its packaged meal replacements, and meals the client cooks. Fuelings include shakes, bars, soups, oatmeal, pancakes, puddings and mug cakes. The company describes its weight-loss Fuelings as "portion-, calorie-, carb-controlled meal replacements" with protein, fiber, probiotic cultures and added vitamins and minerals (Trilivy, n.d.-c). The vanilla shake checked for this page lists soy protein isolate, sugar, soluble corn fiber and whey protein concentrate as its main ingredients, followed by its added vitamins and minerals, and it contains milk and soy (Trilivy, n.d.-c).

On the main weight-loss plan, now called the Reset 5 & 1 Plan and earlier sold as the Optimal Weight 5 & 1 Plan, a person eats 5 Fuelings and 1 Lean & Green meal each day, spaced 2 to 3 hours apart, and the company recommends at least 64 ounces of water a day (Trilivy, n.d.-j). The Lean & Green meal is 5 to 7 ounces of lean protein, up to 2 servings of healthy fat and 3 servings of non-starchy vegetables (Trilivy, n.d.-j). In the company's 2019 trial, this plan was described as providing 800 to 1,000 calories a day, with 80 to 120 grams of protein, 80 to 100 grams of carbohydrate and 20 to 30 grams of fiber (Arterburn et al., 2019).

Other plans loosen the structure. The company's second phase, now called Refine, uses 2 higher-protein Fuelings from its ASCEND line, 2 self-made meals, at least 1 whole-food snack, a daily multivitamin and omega-3 pack, and up to 2 servings of an amino acid product, and the company says fruit, dairy and whole grains come back in this phase (Trilivy, n.d.-m). The company also sells a plan for people taking GLP-1 weight-loss medications, built from 3 ASCEND products, 1 self-made meal and the supplement pack (Medifast, Inc., 2026a).

What you avoid or limit

On the Reset plan, ordinary meals and snacks are replaced: the day is 5 Fuelings and the one Lean & Green meal, and the self-made meal is limited to lean protein, healthy fat and non-starchy vegetables (Trilivy, n.d.-j). Fruit, dairy foods and whole grains are not part of the self-made meal in this phase; the company lists them as foods added in Refine (Trilivy, n.d.-m). The structure is the plan's design rather than a rule enforced by anyone, and the company says clients can change or cancel their orders at any time (Trilivy, n.d.-j).

The plan also limits exercise. The company says the Reset 5 & 1 Plan is not appropriate for people who exercise more than 45 minutes a day or do high-intensity activity, and its disclaimer says the same of its separate "Active" plan (Trilivy, n.d.-f). In the 2019 trial, exercise was suggested only up to 45 minutes a day "due to the caloric content of the meal plan" (Arterburn et al., 2019).

Where it came from

Medifast, Inc. describes itself as physician-founded, with roots in structured nutrition programs for obesity in clinical settings in the 1980s (Trilivy, n.d.-a). Its 2016 annual report said its products had been "recommended by over 20,000 doctors since 1980" (Medifast, Inc., 2017), and the company was incorporated in Delaware in 1989 (Medifast, Inc., 2026a). For years it sold through several channels at once: directly to customers online and by phone, through franchised Medifast Weight Control Centers staffed with counselors, through physicians, and through a coaching business called Take Shape For Life, whose independent contractors were called Health Coaches (Medifast, Inc., 2017).

In July 2016 Take Shape For Life introduced a product line under the name OPTAVIA (Medifast, Inc., 2017). By the company's 2017 annual report, OPTAVIA was the name of the coaching business, the company had stopped selling through medical practices, and it was moving its direct customers into the coach model (Medifast, Inc., 2018). The program's behavior-change materials, the Habits of Health, come from Dr. Wayne Scott Andersen, a physician the company describes as having left critical care medicine to build them (Trilivy, n.d.-a); its 2016 annual report described the author of those books as a co-founder of Take Shape For Life (Medifast, Inc., 2017).

In October 2025 the company announced a shift toward what it calls metabolic health (Medifast, Inc., 2026a). In March 2026 it agreed to nominate 2 people from an investment firm holding more than 5 percent of its shares to its board, and it announced that its chief executive officer would step down from that role on June 1, 2026, with the company's president expected to succeed him (Medifast, Inc., 2026b); by August, Nick Johnson was reporting results as chief executive officer (Medifast, Inc., 2026c). On July 17, 2026, it announced that OPTAVIA would become Trilivy, with reformulated Fuelings to follow in August (Medifast, Inc., 2026d). The company's own page tells visitors that "OPTAVIA has officially become Trilivy" and that account information and autoship settings are unchanged (Trilivy, n.d.-g).

The company's filings describe a shrinking business. Revenue in 2025 fell 36 percent, to $385.8 million, and the number of active earning coaches fell from 27,100 at the end of 2024 to 16,100 at the end of 2025 (Medifast, Inc., 2026a). In the second quarter of 2026 there were 11,700, against 22,800 a year earlier, a decline the company attributes mainly to pressure on finding new clients, including "rapid adoption of GLP-1 medications for weight loss," and it expects the number to keep falling during 2026 (Medifast, Inc., 2026c).

What it claims to do

The company's current pages say the program uses what it calls "Metabolic Synchronization" to reverse metabolic dysfunction through 3 phases named Reset, Refine and Renew (Trilivy, n.d.-d). For the Reset 5 & 1 Plan, its plan page lists "Reverses metabolic dysfunction," "Reduces bad visceral fat by 14%" and "Preserves 98% lean mass," citing the 2019 trial (Trilivy, n.d.-j). The Reset page says the plan is "Ideal for those struggling with" excess weight, stubborn belly fat, bloating, fatigue, brain fog, hormonal imbalances and cravings, and "Also suitable for those taking or looking to transition off GLP-1 medications" (Trilivy, n.d.-k).

On coaching, the company says clients supported by a coach "Lose up to 10x more weight" and "Lose up to 17x more fat" (Trilivy, n.d.-b). The same page states that "Average weight loss on the Trilivy Reset 5 & 1 Plan is 12 pounds" and that clients are in weight loss for 12 weeks on average, and it presents becoming a coach as a way to "Earn income while helping others rebuild their metabolic health" (Trilivy, n.d.-b). These are the company's claims; section 4 sets each one beside the research it cites.

What it gets right

Several features match mainstream guidance. The self-made meal is built on lean protein and non-starchy vegetables, and among the features of a heart-healthy eating pattern the American Heart Association lists eating plenty of vegetables and choosing healthy sources of protein (Lichtenstein et al., 2026). The plan gives a person a clear structure, portions already measured and few daily food decisions, which the authors of one trial suggest may make a meal replacement plan easier to follow (Davis et al., 2010). The company's behavior-change materials cover sleep, movement, the mind and a person's surroundings as well as eating (Trilivy, n.d.-j).

Some of the company's own framing is careful. It tells clients to talk with a healthcare provider before starting and during the program, names the medicines that need a prescriber's attention, warns about gallstones and other effects of rapid weight loss, and states that its coaches are not healthcare professionals and do not provide medical advice (Trilivy, n.d.-e, n.d.-f). It publishes an income disclosure statement showing what its coaches earned, including the share who earned nothing (Trilivy, 2026). These are parts a health and wellness coach can acknowledge in a client's choice without endorsing the program.

How clients describe it, and what it gets confused with

Clients say "I'm on Optavia," "I'm doing the 5 and 1," "I'm on plan," "my Fuelings," "my Lean and Green," "my coach," and, since July 2026, "Trilivy" or "the Reset." Some still say Medifast or Take Shape For Life, the older names for the same company's products and coaching business (Medifast, Inc., 2017). A client may also be a coach in the program, or may have been invited to become one.

It is often grouped with other packaged-meal programs, such as Jenny Craig and Nutrisystem, and with WeightWatchers and Noom; the Meal Replacement Programs page covers shakes and bars as a category.

It is different from the clinician-run formula programs on the Very Low Calorie Diets page, although its main plan's calorie level falls in the range clinical guidance calls a low-energy diet, which that page explains (National Institute for Health and Care Excellence, 2025). Because the company describes a "fat-burning state" (Trilivy, n.d.-c), some clients confuse it with the Ketogenic Diet, which that page describes as restricting carbohydrate usually to 50 grams a day or less; the 5 & 1 plan was described in its trial as providing 80 to 100 grams (Arterburn et al., 2019). Because coaches recruit other coaches, it is also compared with multi-level marketing nutrition companies; the company's annual report says "We are often compared to diet and weight loss-only companies or to multi-level marketing companies, but our model is different" (Medifast, Inc., 2026a).

2. In practice

A typical day of eating

The day described here is this page's own illustration, built from the company's Reset plan schedule (Trilivy, n.d.-j). Breakfast is a Fueling, such as an oatmeal packet or a shake mixed with water. Mid-morning is a second Fueling, perhaps a bar, and lunch is a third, perhaps a soup. Mid-afternoon brings a fourth, a shake or a pudding. Dinner is the Lean & Green meal: about 6 ounces of grilled chicken or fish, a large salad and a cup of roasted broccoli, with a teaspoon of olive oil. A fifth Fueling comes in the evening. Water fills the gaps. Five of the 6 eating occasions come out of a packet, so the cooking and shopping shrink to one meal a day, and the budget moves from the grocery store to the company's shipments.

Cost, products, and who profits

The prices on this page were checked on the company's pages on October 11, 2026. The Reset 5 & 1 Plan kit holds 140 Fuelings and lists for $480; a first order placed on the company's Premier+ autoship program is $384 (Trilivy, n.d.-i). At 5 Fuelings a day, 140 last 28 days, which works out to about $17.14 a day at the list price and $13.71 a day on that first discounted order, before groceries for the Lean & Green meals and before shipping. Autoship orders over $350 get 20 percent off the first order and 15 percent off later ones, and they ship every 28 days unless the client changes the date (Trilivy, n.d.-l). The same autoship page gives the flat shipping charge as $9.95 in one place and $7.95 in another (Trilivy, n.d.-l).

Single boxes of 7 Fuelings sell separately; the vanilla shake box is $24 (Trilivy, n.d.-c). The Refine plan lists for $404, or $323.20 on a first autoship order (Trilivy, n.d.-m).

There is no separate fee for the coach. The coach is paid through the company's compensation plan, and the company's results show coach pay rising and falling with sales: in the second quarter of 2026 it reported a $12.6 million decrease in coach compensation "on lower volume and fewer active earning coaches" (Medifast, Inc., 2026c). The company describes its coaches as independent contractors who market its products to friends, family and others, mostly by word of mouth, email and social media, and says that products are shipped straight to clients (Medifast, Inc., 2026a); its 2017 annual report said that coaches paid the same price for products as their clients (Medifast, Inc., 2018). To become a coach, a person buys a $199 coach kit that includes 12 months of access to a personal website, business education and a smart scale, and later renews a license (Trilivy, n.d.-b).

The company publishes what its coaches earn. Its income disclosure statement for 2025, covering all of its independent coaches in the United States, including those who earned nothing, shows that 23.28 percent earned nothing, that about 57 percent earned $500 or less for the year, that about 70 percent earned $1,000 or less, and that about 1.4 percent earned more than $50,000. These are gross earnings paid by the company; they do not include the expenses coaches had in building their businesses, so they are not profit (Trilivy, 2026). The company states that it "makes no guarantee of financial success" (Trilivy, 2026).

Its annual report notes that a 2024 Federal Trade Commission staff report reviewed the income disclosure statements of 70 multi-level marketing companies, including OPTAVIA's, and found problems across the statements as a group, such as most omitting key information (Medifast, Inc., 2026a). The annual report does not say which findings, if any, applied to OPTAVIA's statement, and this page did not open the commission's report, so it draws no conclusion about this company from it.

The people who make money when a client follows the program are Medifast, Inc. and its shareholders; its manufacturing subsidiary, which makes about 40 percent of its units, and the outside manufacturers that make the rest; and the coaches, through the compensation plan (Medifast, Inc., 2026a). Because the company describes its coaches as its most effective way of finding new clients (Medifast, Inc., 2026a), the person who first describes the program to a client is often someone who earns from the client's purchases. That shapes the information a client has already heard before a coaching conversation begins.

The searches for this page did not identify a study of what the program costs a household compared with ordinary groceries. What follows is observation rather than measured data. The products remove most of the cooking, which helps a person with little time, but at roughly $14 to $17 a day for the Fuelings alone, the program costs more than many households spend on food, and a person with limited money may find the autoship the hardest part to keep up.

Environmental footprint

The searches for this page did not identify a study of the environmental footprint of this program. A 2023 study modeled the greenhouse gas emissions and water use of 7 commercial weight-loss diet patterns from the companies' published guidelines and sample meal plans, counting emissions up to the farm gate, and did not include this program (Neff et al., 2023); it is not an estimate for any packaged product. Whatever the balance is, it depends on two things this page could not measure: the manufacture, packaging and shipping of single-serving Fuelings every 4 weeks, and the protein a person chooses for the Lean & Green meal.

Cultural fit

This is a description of the plan rather than a research finding. On the Reset plan, 5 of 6 eating occasions are company products, so the foods of a person's own tradition appear only in the one self-made meal, and only as lean protein and non-starchy vegetables. Rice, tortillas, bread, beans, fruit and dairy foods, staples in many kitchens, wait until a later phase (Trilivy, n.d.-m). Eating every 2 to 3 hours can be hard to fit into a workday or a household that eats together at fixed times, and family meals mean cooking a separate plate or eating a Fueling beside everyone else. The products contain milk and soy (Trilivy, n.d.-c), which matters for a person who avoids either. For a person who does not cook, dislikes deciding what to eat, or lives alone, the same structure can be the attraction.

What makes people stop

The trials give some sense of how hard the plan is to keep. In the 2019 trial, the coached group's own rating of how well they were following the program fell from 75 percent after 4 weeks to 63 percent after 16 weeks, and they completed an average of 16 of 23 scheduled coaching calls (Arterburn et al., 2019). In a 40-week trial of the same meal plan without a coach, 62 percent of the meal-plan group completed the first 16 weeks and 58 percent were still in the study at 40 weeks (Davis et al., 2010). In a 52-week trial, 83 percent of the meal-plan group completed the year on the assigned plan, against 75 percent of the food-based group (Shikany et al., 2013). The company states that its clients are in weight loss for 12 weeks on average (Trilivy, n.d.-b).

Beyond those figures, what follows is observation: cost, the sameness of packaged food, meals with family and friends, travel, and the change in the relationship if the coach is a friend or relative are the reasons a person is likely to stop. The company's own annual report notes that its coaches are "subject to high turnover" (Medifast, Inc., 2026a), so a client may also lose the coach who brought them in.

What happens when you stop

The searches for this page did not identify a trial that followed people on the coached program or the 5 & 1 plan for more than 1 year. One trial of the company's diabetes products, at a different calorie level, followed adults with type 2 diabetes to 86 weeks, including a year of maintenance, and its abstract reports better maintenance on the meal replacement diet than on a standard diet (Cheskin et al., 2008). This page read only that abstract, which does not say whether participants kept using the products through the maintenance year, so following people to 86 weeks is not the same as 86 weeks on the plan.

The two longer trials of the same meal plan show partial regain once the weight-loss phase ends. In the 40-week trial, the meal-plan group regained an average of 4.8 kilograms during a 24-week maintenance phase, against 0.8 kilograms in the food-based group; at 40 weeks the meal-plan group was 8.9 kilograms below its starting weight and the food-based group 5.7 kilograms below, a difference in body mass index the trial could not distinguish from chance (Davis et al., 2010). In the 52-week trial, the meal-plan group's average loss went from 7.5 kilograms at 26 weeks to 4.7 kilograms at 52 weeks, and the food-based group's from 3.8 to 1.9 kilograms (Shikany et al., 2013). These are measured weights, reported as measurements.

The company's own scientists, in a 2026 review of the research on its meal plans, wrote that the studies were short, from 4 to 26 weeks, that "long-term durability data are needed," and that the benefits of weight-loss programs using meal replacements are often followed by regain if the plans or supports are withdrawn (Miller et al., 2026). The program's answer is a maintenance phase built on its ASCEND products (Trilivy, n.d.-m); the searches for this page did not identify a trial of that phase.

Common variations

The current plans are the Reset 5 & 1 Plan, the Reset 5 & 1 Active Plan, and a Reset option the company offers to people with less than 15 pounds to lose, followed by the Refine and Renew phases (Trilivy, n.d.-d, n.d.-f). The company also sells a teen plan, which its disclaimer calls the only plan appropriate for ages 13 to 17 (Trilivy, n.d.-f), and a plan for people taking GLP-1 medications (Medifast, Inc., 2026a).

Clients may use older names: the Optimal Weight 5 & 1 Plan, the Optimal Weight 4 & 2 & 1 Plan, which had 4 Fuelings, 2 self-made meals and a snack at about 1,100 to 1,300 calories (Arterburn et al., 2019), and the Medifast plans once sold directly and in weight control centers (Medifast, Inc., 2018). The clinician-run formula programs on the Very Low Calorie Diets page are a separate thing, although the 5 & 1 plan's calorie level is in the low-energy range that page describes.

3. For the coach

SCOPE OF PRACTICE

A health and wellness coach does not prescribe, adjust, endorse, or discourage Optavia or any other way of eating, and does not diagnose or treat. The coach helps the client understand what they have chosen, notice how it is going, and decide what to do next.

Two different roles share the word coach. The company describes its coaches as independent contractors who market its products and support clients, and says that about 90 percent of them were clients first (Medifast, Inc., 2026a). A person becomes one by buying a $199 coach kit (Trilivy, n.d.-b); the company says its coaches complete a program-specific curriculum developed by registered dietitian nutritionists and behavior change experts and must pass an annual certification exam, and that they are not healthcare professionals and do not provide medical advice (Trilivy, n.d.-e, n.d.-h). Its annual report adds that most of its coaches do not have extensive training or certification in nutrition, diet or health fields beyond the education the company gives them, and its coaches are paid through a compensation plan that moves with sales volume (Medifast, Inc., 2026a, 2026c).

A National Board Certified Health and Wellness Coach has completed a training program approved by the National Board for Health & Wellness Coaching, logged 50 qualifying coaching sessions after passing a practical skills assessment, met an education or work-experience requirement, and passed the board examination (National Board for Health & Wellness Coaching, n.d.-a, n.d.-b). The board's scope of practice says that coaches, on their own, do not provide nutrition consultation or create meal plans (National Board for Health & Wellness Coaching, n.d.-c), and its code of ethics asks coaches to disclose any compensation from selling products to clients before coaching begins and not to make coaching depend on a client buying anything (National Board for Health & Wellness Coaching, 2025).

One person can hold both roles. The board's scope of practice says coaches should take on dual roles only with conscious intention, outlining both roles and their boundaries with the client through discussion and documentation (National Board for Health & Wellness Coaching, n.d.-c). A coach in both roles names the credential they hold before a client decides what to tell them.

The program's main plan supplies about 800 to 1,000 calories a day (Arterburn et al., 2019), a low-energy diet by the definition in England's national clinical guideline, which advises clinical support, a time limit, a nutritionally complete plan and a review of medicines before starting (National Institute for Health and Care Excellence, 2025); the company states that it does not use physicians or nurses to monitor its clients (Medifast, Inc., 2026a). So for any client considering the main plan, the coach can, with permission, share that guidance and support the client in talking with a physician or registered dietitian before starting. For a client in any of these groups, the coach's role includes making sure the client has medical oversight for the change:

• Taking insulin, a sulfonylurea or another medicine that lowers blood sugar: the client keeps the prescriber informed before starting, because eating fewer carbohydrates can bring on low blood sugar.
• Taking blood pressure medicine, a diuretic, warfarin, lithium or thyroid medicine, which the company itself names (Trilivy, n.d.-f): the client keeps the prescriber informed before a substantial change in eating.
• Taking a GLP-1 medication: the prescriber who manages it is part of any decision to combine it with this program.
• Pregnant or breastfeeding, or under 18: the company says not to use its plans in pregnancy or under age 13, and that the main plan is not for teenagers or nursing mothers (Trilivy, n.d.-f); the obstetric or pediatric clinician and a registered dietitian decide.
• Living with kidney disease, which the company asks to be cleared first (Trilivy, n.d.-f): needs depend on the stage, lab results and whether the person is on dialysis, so the kidney care team is involved.
• Living with heart or liver disease, diabetes, cancer, thyroid disease, gout or another condition that weight loss can affect, which the company also asks to be cleared first (Trilivy, n.d.-f): the treating clinician.
• A current or past eating disorder: through the coach’s own referral process or the client's existing care plan.
• An adult 65 or older who is not active, for whom the company says the main plan is not appropriate (Trilivy, n.d.-f): the physician and a registered dietitian.

Who does what

The physician

Decides whether a low-energy plan of about 800 to 1,000 calories a day is medically appropriate for this person and for how long, and reviews the person's medicines before it starts: insulin, sulfonylureas and other diabetes medicines, blood pressure medicines and diuretics, warfarin, lithium, thyroid medicine and any GLP-1 medication. For kidney disease, the decision depends on the stage, lab results and dialysis, with the kidney care team. Follows the measures that change with rapid weight loss, such as blood sugar and blood pressure, and adjusts doses. Evaluates symptoms the company itself warns about, such as abdominal pain that could point to gallstones, dizziness, or a rapid or irregular heartbeat.

The registered dietitian

Checks whether this plan is nutritionally complete for this person and meets their needs, given their health conditions, medicines, food allergies and activity, and adapts or replaces it for diabetes, kidney disease, gout, pregnancy or a teenager. Plans the move back to ordinary food so that it fits the person's budget and food traditions. Offers nutrition guidance that is independent of the sale of any product.

The health and wellness coach

Helps the client get clear about why they chose this program and what they want from it, and test it against their life: the cost each month, family meals, work hours, travel and the foods that matter to them. Helps them plan the hard parts, notice how it is going in their own terms, such as energy, sleep, mood and enjoyment of food, and prepare questions for their physician. When the person who sold them the program is a friend or relative, helps the client sort out what they want from each relationship. Holds the referral line, and keeps out of the product decisions that belong to the client, the clinician and the dietitian.

What a client bringing this diet needs

Clients come to this program for a handful of reasons: a friend, coworker or relative lost weight on it and invited them; they want a plan that decides what to eat; they have tried other approaches and want structure; they are starting or stopping a GLP-1 medication and saw the company's plans for that; or they are thinking about becoming a coach to earn income. The reason shapes the conversation. A coach does not take on a number on the scale as the goal of the work.

The coaching conversation can offer room to think apart from the sale. The company's coaches complete the company's own training, are paid through a compensation plan that moves with sales, and are described by the company as not healthcare professionals; its annual report says most lack extensive training in nutrition, diet or health fields, so individual backgrounds vary (Medifast, Inc., 2026a; Trilivy, n.d.-e). The person who introduced the program may earn from the client's orders, so a client may want a place to weigh it without worrying about that relationship. With permission, the coach can share general information, such as what the trials measured and for how long, or where the company publishes its coaches' earnings, and explore what the client makes of it. The decision stays with the client, inside the referral lines in the scope box.

What to ask

• "What drew you to this program, and what are you hoping will be different in 3 months?"
• "How does the cost and the schedule fit with the rest of your week and the people you eat with?"
• "What will you eat when the Fuelings stop, and what would you like that to look like?"
• "Does your doctor know about the plan, and are you taking any medicines they would want to hear about first?"

Referral red flags

Some of these call for a prompt conversation with a clinician and some for urgent help. A client taking insulin, a sulfonylurea or a meglitinide who reports shakiness, sweating or confusion may be having a low blood sugar episode right now. The first step is the one in their own diabetes plan for treating it, with emergency help if symptoms are severe or they cannot manage the episode under their plan; telling the prescriber is the separate step that follows. Low blood sugar can happen when a person taking these medicines does not eat enough carbohydrate or skips or delays meals (National Institute of Diabetes and Digestive and Kidney Diseases, n.d.-a).

The company itself tells clients to seek immediate medical attention for muscle cramps, tingling, numbness, confusion, or a rapid or irregular heartbeat (Trilivy, n.d.-f). Pain in the abdomen lasting several hours, nausea and vomiting, fever or chills, or yellowing of the skin or eyes during or after an attack can be signs of a gallstone complication, and a federal health agency advises seeing a doctor right away (National Institute of Diabetes and Digestive and Kidney Diseases, n.d.-b). A client who is pregnant, who becomes pregnant, or who is under 18 needs a clinician's involvement before any such plan. Weight a client is losing without meaning to, outside the plan, is also a reason to involve a clinician.

Some patterns call for a closer look at the eating itself: restarting the plan again and again with distress, staying on the most restrictive phase far longer than intended, skipping the Lean & Green meal to lose faster, weighing several times a day, hiding food, or turning down meals with others beyond what the plan asks. Many of these have ordinary reasons, from a work schedule to a household's habits to a dietitian's plan, so on its own a behavior tells a coach little, and none of this is a diagnosis. The coach asks what the behavior is for, whether it causes distress, whether it is narrowing what the person eats, and whether it is getting in the way of daily life. Where the answers raise a real concern, the coach follows their own referral process, or brings the concern to the client's clinician under an existing care plan.

Special populations

Pregnancy and breastfeeding

The searches for this page did not identify a study of the program in pregnancy or breastfeeding. The company's disclaimer says not to use any of its plans while pregnant and that the main plan is not appropriate for nursing mothers (Trilivy, n.d.-f). The trials excluded people who were pregnant or breastfeeding (Arterburn et al., 2019). Any change of this kind belongs with the obstetric clinician and a registered dietitian.

Children and adolescents

The searches for this page did not identify a published trial of the program in children or teenagers. The company says its products are not for children under 13, and that its teen plan is the only one appropriate for ages 13 to 17 (Trilivy, n.d.-f). A coach works with the adult in front of them; a child's or teenager's eating belongs to the family, the pediatric clinician and a registered dietitian.

Older adults

The company says its main plan is not appropriate for sedentary adults 65 and older (Trilivy, n.d.-f). In a 6-month university trial of 96 adults with obesity averaging 70 years old, a weight-loss program built on the company's less restrictive 4 & 2 & 1 plan led to more weight lost than a weight-stable comparison group, mostly as fat, and the trial did not detect a difference between the groups in lean mass change (Beavers et al., 2019). That trial was read as an abstract only and tested a different plan from the one most clients start on. An older client with several medicines or health conditions is a client for a physician and dietitian first.

Athletes and people with high activity

The searches for this page did not identify a study of the program in athletes. The company says its main plan is not appropriate for people who exercise more than 45 minutes a day or do high-intensity activity, and its disclaimer says the same of its separate Active plan (Trilivy, n.d.-f). Whether any plan of this kind meets the energy needs of heavy training is a question for a sports dietitian.

People taking medication for diabetes, blood pressure, or blood thinning

Insulin, sulfonylureas and meglitinides can cause low blood sugar, and eating too little carbohydrate or skipping or delaying meals makes it more likely (National Institute of Diabetes and Digestive and Kidney Diseases, n.d.-a). The company names warfarin, lithium, diuretics and medicines for weight loss, diabetes, high blood pressure and thyroid conditions as ones to discuss with a healthcare provider before starting (Trilivy, n.d.-f). The 2019 trial excluded people with type 2 diabetes who needed medication (Arterburn et al., 2019). The standing rule is that the client keeps the prescriber informed before a substantial change in eating, rather than asking permission for every food choice.

People with a history of disordered eating

The searches for this page did not identify a study measuring disordered eating in people on the program, and the trials excluded people with a history of eating disorders (Arterburn et al., 2019). The company asks anyone with an eating disorder such as anorexia or bulimia to be cleared by a healthcare provider before using its plans (Trilivy, n.d.-f). The plan's features, a fixed schedule of packaged foods and a calorie level of about 800 to 1,000 a day, are the kind that call for that caution. A client with this history is referred to their clinician, or through the coach’s own referral process if they have none, before the program is discussed further.

Client misconceptions

Three come up most. The first is that an Optavia coach and a health and wellness coach do the same job. They share a word but not a role: one is an independent seller of the company's products who completed the company's training, and the other is a professional trained and examined to standards set by a national board, whose scope excludes meal plans (Medifast, Inc., 2026a; National Board for Health & Wellness Coaching, n.d.-c).

The second is that research shows the coach is what makes people lose 10 times as much. The company's figures come from a trial in which the coached group differed from the comparison group in its food, its calorie level and its free products as well as its coaching, and the trial's own authors wrote that conclusions about the separate effects of the plans and the support "were not possible" (Arterburn et al., 2019). The third is that the program is medically supervised because it began with physicians. The company states that it does not use physicians or nurses to monitor clients and that its coaches do not practice medicine (Medifast, Inc., 2026a; Trilivy, n.d.-e). Each is taken up in section 6.

🤝 COACHING CONNECTION

Karen tells her coach that her sister-in-law, an Optavia coach, wants her to start the 5 and 1 plan. Karen likes the idea of not planning meals but is unsure about the cost and about eating differently from her husband and kids. The coach reflects that she sounds both tempted and cautious, and asks what she wants the next 3 months to bring: more energy, she says, and fewer evenings of snacking. The coach asks what she knows about how the plan would fit dinners at home, and whether her doctor knows, since she mentioned taking a blood pressure pill. With permission, the coach adds that clinical guidance advises starting a plan at this calorie level with a clinician's support. Karen decides to call her doctor's office and go over the monthly cost with her husband before answering her sister-in-law. The coach gives no opinion of the program.

4. The evidence

(select the heading to open or close this section)

The research on this program comes almost entirely from studies the company paid for, and much of it from studies its own employees wrote. The strongest of it, 3 randomized trials, found that adults following the company's meal plans lost more weight at 16 to 52 weeks than adults on food-based diets or a self-directed diet, although at 40 weeks the smallest trial did not show a clear difference; the 2 trials that continued after the weight-loss phase saw partial regain. The searches for this page did not identify a trial of the coached program or the 5 & 1 plan longer than 1 year, a trial measuring heart attacks, strokes, cancer or deaths, or a trial that separated the effect of the coaching from the effect of the food.

The research on meal replacements as a category is on the Meal Replacement Programs page and is not repeated here. The certainty ratings are in the Evidence rating and review record at the end of the page.

Evidence from randomized controlled trials

A trial assigns people to a program by chance and compares them with people assigned to something else, which is the strongest way to test whether the program itself causes a result. With a commercial program, which version was tested matters, because the company has sold the same meal plans with an Optavia coach, without one, and in clinics. The trials found for this page tested 3 different things: the coached program itself; the same 5 & 1 meal plan sold without a coach; and related company plans in particular groups.

In a 2026 review, the company's own scientists counted 9 unique randomized trials among 17 publications from 2010 to 2025, lasting 4 to 26 weeks (Miller et al., 2026), while the company's consumer page says its record includes "18 randomized controlled trials" (Trilivy, n.d.-e). The 2 numbers may count different things: the review included only publications from 2010 to 2025 that met its criteria and counted each trial once however often it was published, and the consumer page does not say what its 18 includes. A difference in what is counted does not by itself show that either number is wrong.

Body weight, as measured: the coached program

The one trial of the coached program was run in 2016 and 2017 at a single research center near Chicago, funded by the company, with 4 of its 8 authors paid by the company and the other 4 by the research firm that ran it (Arterburn et al., 2019). It randomized 198 adults aged 18 to 65 with a body mass index of 27 to 42, 80.8 percent of them women, to 3 groups for 16 weeks. One group followed the Optavia 5 & 1 Plan at about 800 to 1,000 calories a day with 23 scheduled telephone calls from a coach. A second followed the company's self-guided Medifast 4 & 2 & 1 Plan at about 1,100 to 1,300 calories. The third received a personal calorie target, a federal MyPlate meal plan and a 10 to 15 minute introduction, and followed it on its own.

Both company groups received their products free, and all participants were paid stipends for clinic visits (Arterburn et al., 2019).

Of the 198, 184 completed the 16-week assessment, and 194 were included in the main analysis. Average weight change was a loss of 5.2 kilograms in the coached group, 5.0 kilograms in the self-guided group and 0.2 kilograms in the self-directed diet group, and the results were similar whichever way missing data were handled. Among those analyzed, 28.1 percent of the coached group, 14.9 percent of the self-guided group and 1.6 percent of the self-directed group lost at least 10 percent of their starting weight (Arterburn et al., 2019). These are measured weights at 16 weeks, reported as measurements; the archive does not treat weight change as the measure of whether a program worked.

Four limits matter. First, the coached group differed from the self-directed group in its food, its calorie level, its free products and its coaching all at once, and the authors state that no comparisons between the 2 company groups were prespecified and that, because the groups had different meal plans and different support, "definitive conclusions about the relative impact of these independent variables were not possible" (Arterburn et al., 2019). Second, the coaches were research assistants trained to act as Optavia coaches, with no prior coaching experience, not the program's own coaches (Arterburn et al., 2019). Third, the self-directed group lost almost nothing, which the authors note is similar to self-directed groups in other trials. Fourth, 16 weeks says nothing about what happens next, and the trial excluded people with medicated diabetes, eating disorders or pregnancy (Arterburn et al., 2019).

Within the coached group, people who completed more of their calls lost more weight: those who completed at least 17 of the 23 calls lost an average of 6.9 kilograms, against 3.1 kilograms for those who completed fewer (Arterburn et al., 2019). That is a comparison people made by their own behavior, not by chance, so it cannot show that the calls caused the difference; people who keep appointments may also follow a plan more closely.

Body weight, as measured: the same meal plan without a coach

Two earlier trials tested the 5 & 1 meal plan without an Optavia coach, each against a food-based diet set at about the same calorie level. In the first, 90 adults with a body mass index of 30 to 50 were randomized to the plan or to a food-based diet of about 1,000 calories a day for 16 weeks, then followed through a 24-week maintenance phase, with both groups seeing a dietitian every 2 weeks during weight loss (Davis et al., 2010).

Only 28 of 45 in the meal-plan group and 20 of 45 in the food-based group completed the first 16 weeks, and the paper reports results only for those who completed. Among them, the meal-plan group lost 12.3 percent of its starting weight at 16 weeks and the food-based group 6.7 percent; the abstract gives 6.9 percent for the same figure. At 40 weeks the groups were 7.8 and 5.9 percent below their starting weight, and the difference in body mass index was not statistically significant (Davis et al., 2010). Six of the authors were company employees, and one held company stock.

In the second, run by university investigators and supported by the company, 120 adults with a body mass index of 35 to 50 were randomized to the 5 & 1 plan, as the company then sold it directly by phone and online with an online community, or to a 1,000-calorie food-based diet, for 26 weeks of weight loss and 26 weeks of maintenance (Shikany et al., 2013). In the published abstract, 50 of 60 in the meal-plan group and 45 of 60 in the food-based group completed the year on their assigned plan. In the trial's main intention-to-treat analysis, adjusted for race, the meal-plan group lost 7.5 kilograms at 26 weeks against 3.8 in the food-based group, and at 52 weeks the figures were 4.7 and 1.9 kilograms (Shikany et al., 2013).

This page read the abstract and the authors' accepted manuscript, not the published article, so it uses only the numbers in the abstract.

A third trial gave every participant free Medifast products on the Take Shape For Life 5 & 1 plan, with weekly telephone calls from pharmacy students in a support system patterned on the company's coaching and its Habits of Health materials, and randomly added either the appetite-suppressing medicine phentermine or a placebo for 12 weeks (Moldovan et al., 2016). The abstract reports 77 adults with obesity. The full article reports that 96 people were selected, 9 did not meet the entry criteria, 87 were randomized, and 10 were then left out of the analyses because their baseline information was incomplete, leaving 77 analyzed. Among those 77, the phentermine group lost 12.1 percent of its starting weight and the placebo group 8.8 percent. One participant had high blood pressure during the study, which was managed by tapering the phentermine dose (Moldovan et al., 2016).

Because everyone was on the meal plan, the randomized comparison tests the medicine, not the program: the trial cannot show what the program adds over other approaches, or how safe the program is for people buying it on their own. This page read the published article.

Body weight, as measured: independent reviews

A 2015 systematic review of commercial weight-loss programs, written by researchers independent of the company, grouped Medifast with other very-low-calorie programs and reported that these programs "resulted in at least 4.0% greater short-term weight loss than counseling, but some attenuation of effect occurred beyond 6 months when reported" (Gudzune et al., 2015). Its authors' accepted manuscript shows that the review included one Medifast trial, the 40-week trial above, classed it as a comparison with counseling, and rated its risk of bias as high in both its text and its summary table. The published abstract and accepted manuscript were read. The correction notice says the Medifast study reported no serious harms and identifies no change to its weight results or risk-of-bias label. The corrected published article and supplement remain unchecked.

A 2021 update by the same group listed Medifast among programs that "have demonstrated 12-month weight loss efficacy and safety" (Laudenslager et al., 2021). This page read that review's published abstract and its accepted manuscript, which notes that 3 of the 5 Medifast trials it reviewed reported only completers, and did not read the published article. Both reviews concern the company's meal plans; neither isolates the Optavia coaching model.

Body composition

The 2019 trial measured body composition with a dual-energy X-ray scan. In the coached group, average fat mass fell by 4.53 kilograms and lean mass by 0.68 kilograms, against 0.22 and 0.01 kilograms in the self-directed group, and visceral fat, the fat around the organs, fell by 239 grams against 8 grams (Arterburn et al., 2019). The coached group therefore lost more lean mass than the comparison group, as is expected when more weight is lost; the company's figure of 98 percent of lean mass retained is the same result expressed the other way, a loss of 1.49 percent of starting lean mass (Arterburn et al., 2019).

In older adults on the company's 4 & 2 & 1 plan for 6 months, about 87 percent of the mass lost was fat, and the trial did not detect a difference in lean mass change between the weight-loss and weight-stable groups (Beavers et al., 2019).

Cardiometabolic outcomes

The trials of the program measured few blood markers. In the 2019 trial, C-reactive protein, a marker of inflammation, did not differ significantly between the coached and self-directed groups in the main analysis (Arterburn et al., 2019). In the 40-week trial, both groups improved on blood and clinical measures, and only the meal-plan group showed significant improvements in diastolic blood pressure, waist circumference and a marker of oxidative stress by 40 weeks, among those who completed (Davis et al., 2010). The company's 2026 review of its own research described decreases in blood pressure across studies, with statistical significance varying, and called the results for blood lipids and blood sugar mixed (Miller et al., 2026).

For people with type 2 diabetes, a 34-week trial of 119 adults compared a portion-controlled meal replacement diet with a standard diet based on American Diabetes Association recommendations, both set at 75 percent of each person's predicted energy needs, followed by a year of maintenance; the trial was registered as testing the company's Medifast Plus for Diabetics products, with the company as a collaborator (Cheskin et al., 2008; Johns Hopkins Bloomberg School of Public Health, n.d.). In the abstract, weight loss at 34 weeks and maintenance at 86 weeks were better on the meal replacement diet, about 40 percent against 12 percent lost at least 5 percent of their weight, and both groups improved on biochemical measures (Cheskin et al., 2008). This page read the abstract only, which does not report blood sugar results, so none are reported here.

Heart attacks, strokes, cancer and death

The searches for this page did not identify a trial or cohort study of the program, or of the company's meal plans, that measured heart attacks, strokes, cancer or deaths. The trials found lasted from 12 to 86 weeks and were not designed or large enough to count such events, so the studies reviewed do not establish whether the program affects them in either direction.

Eating behavior and wellbeing

In the 2019 trial, quality of life scores improved in all 3 groups, and the coached group's scores did not differ significantly from the self-directed group's; within the coached group, more completed calls went with better scores on some measures (Arterburn et al., 2019). In the phentermine trial, food cravings fell in both groups on the program (Moldovan et al., 2016). The searches did not identify a study of eating disorder symptoms or disordered eating in people on the program.

Evidence from long-term prospective cohort studies

A cohort study follows people who already eat a certain way and records what happens to them. The searches for this page did not identify a cohort study of people on the program, so they supply no cohort evidence about cardiometabolic outcomes, cancer, body weight or death in people who follow it.

Studies without a comparison group

The company has also published reviews of client records from its Medifast Weight Control Centers, a center-based model with counselors that had shrunk to 16 franchise centers by the end of 2017 and is not described in its 2025 annual report (Medifast, Inc., 2018, 2026a). In one, of 310 clients on the 4 & 2 & 1 plan at 21 centers, 185 were still on the plan at 12 weeks and had lost an average of 10.9 kilograms, and 81 were still on it at 24 weeks (Coleman et al., 2015). Another, of 816 records, found similar weight loss among clients with and without diabetes who stayed on the program (Coleman et al., 2017). These reviews count only people who stayed, have no comparison group, describe a model other than the current coach program, and were written by company employees. This page read their abstracts.

A 2022 online survey by the company's scientists studied 590 coaches and clients who reported losing at least 10 percent of their weight on the program and keeping most of it off for at least a year; 342 of them were coaches (Coleman et al., 2022). Its authors concluded that becoming a coach was a strategy unique to the program among successful maintainers. Because the survey asked only people who had succeeded, with weights they reported themselves, it cannot show how common lasting weight loss is or whether becoming a coach causes it. The company's coach page cites this survey for its statement that people who contribute to the health and well-being of others tend to be more successful at maintenance (Trilivy, n.d.-b).

The company's claims, examined

The claims a client is most likely to have heard deserve a close look, because seeing what a claim rests on is a skill a coach can use with any product. The company says clients with a coach "Lose up to 10x more weight" and "up to 17x more fat," citing the 2019 trial, and its program page gives the figures as 12.08 pounds of weight and 9.57 pounds of fat for the coached group against 1.12 and 0.55 pounds for the control group (Trilivy, n.d.-b, n.d.-d).

The paper's main results table reports average losses of 5.2 kilograms against 0.2 kilograms for weight and 4.53 against 0.22 kilograms for fat in its main analysis (Arterburn et al., 2019). The company's pound figures do not appear in the paper, and the company does not say which participants or which analysis they come from, so this page could not check them against the published results: they are not verifiable from the paper, which is different from being shown to be wrong. Any ratio against a comparison group that lost almost nothing will be large; the paper itself compares the groups in kilograms and percent, not as a ratio.

A company article says the trial "isolated coaching as a measurable variable" and that clients who worked with a coach lost up to 10 times more "than those who attempted the program without coaching support" (Trilivy, n.d.-e). In the trial, the comparison group did not attempt the program: it followed a self-directed food-based diet without the company's products, and the group that used the products without a coach, on a different plan, lost almost as much as the coached group (Arterburn et al., 2019). The company's annual report also describes the trial as "a double-blind study" (Medifast, Inc., 2026a); the paper names as a weakness "the inability to mask study groups," with only the statistician blinded (Arterburn et al., 2019).

The plan page's "Reduces bad visceral fat by 14%" cites the same trial (Trilivy, n.d.-j). The paper reports visceral fat as an average change in grams, a fall of 239 grams in the coached group, not as a percentage (Arterburn et al., 2019). A percentage depends on which people and which analysis are used: the average of each person's percentage change is not the same as a group's average change divided by its average starting amount. Because the paper reports no percentage change, the 14 percent figure cannot be verified from its published analysis. The trial did not measure the metabolic dysfunction the company says the plan reverses.

The company's statement that more than 90 percent of U.S. adults are metabolically unhealthy (Medifast, Inc., 2026a; Trilivy, n.d.-e) cites a national study that found 6.8 percent of adults had optimal levels on all of 5 measures of cardiometabolic health: body fat, blood sugar, blood lipids, blood pressure and the absence of cardiovascular disease (O'Hearn et al., 2022). Not reaching optimal levels on all 5 includes many people at intermediate levels, which is not the same as having a dysfunction.

The reformulated Fuelings add what the company calls MetaVantage Technology, which it says helps reduce waist circumference, citing a trial of a probiotic strain (Trilivy, n.d.-c). That trial gave 135 adults with abdominal obesity a daily capsule of the strain, live or heat-killed, or a placebo for 3 months, and reported smaller waist measurements than at the start with the live strain, with differences from placebo reaching significance for the heat-killed form (Pedret et al., 2019). It tested capsules of one ingredient, not Fuelings, and this page did not find how much of the strain a Fueling contains. More generally, an independent study of commercial programs' websites found that the weight losses shown in testimonials exceeded those achieved in the programs' trials (Vakil et al., 2017).

Highlighted studies

These 4 carry the most weight for this program. Each is described so a reader can judge it without opening the paper.

On a narrow screen, scroll the table sideways to see every column.

Highlighted studies for Optavia

Study	Design	Sample size	Duration	Finding	The limitation that matters
Arterburn et al., 2019	Randomized controlled trial, 3 groups, funded by the company and partly written by its employees	198 adults randomized; 194 analyzed; 184 completed the 16-week assessment	16 weeks	The coached 5 & 1 group lost an average of 5.2 kilograms, the self-guided 4 & 2 & 1 group 5.0, and the self-directed diet group 0.2	The coached group differed from the comparison group in food, calories, free products and coaching all at once, and the coaches were trained research assistants
Shikany et al., 2013	Randomized controlled trial, university-run, supported by the company	120 adults randomized; 50 of 60 and 45 of 60 completed the year on their assigned plan	52 weeks: 26 of weight loss, 26 of maintenance	The 5 & 1 plan group was 4.7 kilograms below its starting weight at 52 weeks, against 1.9 for a food-based diet of similar calories	Tested the plan sold directly by phone and online, without an Optavia coach; read as the abstract and the authors' manuscript, not the published article
Davis et al., 2010	Randomized controlled trial, funded by the company and written mostly by its employees	90 adults randomized; 48 completed 16 weeks; 46 completed 40 weeks	40 weeks: 16 of weight loss, 24 of maintenance	Among completers, the 5 & 1 group lost 12.3 percent of body weight at 16 weeks, against 6.7 percent on a food-based diet; at 40 weeks the difference in body mass index was not statistically significant	About 4 in 10 of each group left the study, and results are reported only for those who stayed; both groups also saw a dietitian
Gudzune et al., 2015	Systematic review of trials of commercial weight-loss programs, independent of the company	45 studies, 39 of them randomized trials, across many programs	Trials of at least 12 weeks	Grouped Medifast with very-low-calorie programs, which produced at least 4.0 percent more short-term weight loss than counseling, with some attenuation beyond 6 months when reported	Abstract and accepted manuscript read; correction notice reports no serious harms for Medifast, without identifying weight-result or risk-of-bias changes. Corrected published article and supplement unchecked; predates the coached trial.

Head to head

The 2019 trial ran the coached Optavia plan beside the company's self-guided Medifast plan, and the groups lost similar amounts at 16 weeks, but the trial was not designed to compare them and the plans differed in calories as well as support (Arterburn et al., 2019). The searches for this page did not identify a trial comparing the program with WeightWatchers, Noom, other meal replacement brands or another named diet. The 2015 review compared programs only indirectly, across separate trials (Gudzune et al., 2015).

Where the evidence is absent

The searches for this page, run on October 11, 2026 in Europe PMC, PubMed and ClinicalTrials.gov, including a separate search for each special population this archive covers, did not identify a study of the coached program or the 5 & 1 plan that lasted more than 52 weeks, a study of the program that measured heart attacks, strokes, cancer or deaths, or isolated the effect of the coaching from the food plan. They did not identify a trial of the current Trilivy plans or reformulated Fuelings, of the maintenance phase, or of the plan for people taking GLP-1 medications.

Nor did they identify a study of the program in pregnancy, breastfeeding, children, adolescents or athletes, a study of disordered eating in people on it, or a study of what it costs a household or of nutrient intake on the current plans. The trials found excluded people with medicated diabetes, eating disorders or pregnancy, or were small. The studies reviewed for this page do not establish that the program has effects beyond short-term weight and body composition changes, and they do not establish that it lacks them. These searches did not cover every database, regulator or court.

5. Mechanisms

(optional reading; select the heading to open or close this section)

This section explains how the program is thought to work in the body. You can skip it. Nothing in the coaching sections depends on it.

Established mechanisms

The plan's main lever is the number of calories it supplies, about 800 to 1,000 a day (Arterburn et al., 2019), and a 2015 review grouped the company's plans with very-low-calorie programs (Gudzune et al., 2015). In the 2 trials that set the comparison diet at about the same calorie level, the meal plan still produced more weight loss, and the authors of one suggest the reason is that a plan of pre-portioned products is easier to follow than a plan a person assembles from ordinary food (Davis et al., 2010). That points to adherence, not a special property of the products, and the research on meal replacements as a category is on the Meal Replacement Programs page.

The plan's protein, about 80 to 120 grams a day (Arterburn et al., 2019), is relevant to what is lost. Body composition scans in the trials found that most of the weight lost was fat, with a smaller loss of lean mass (Arterburn et al., 2019; Beavers et al., 2019). These studies measured the result; they were not designed to show which part of the plan caused it.

Proposed mechanisms

The company offers explanations of its own. It says its system works through "Metabolic Synchronization," which it describes as bringing the body's energy use, fat burning and muscle preservation into harmony (Trilivy, n.d.-d); that its Fuelings put the body in a "strong and targeted fat burning state" (Trilivy, n.d.-c); and that eating every 2 to 3 hours supports blood sugar stability and appetite control (Trilivy, n.d.-j). These are the company's claims. The searches for this page did not identify a peer-reviewed study defining or testing Metabolic Synchronization, or a study testing whether the plan's meal spacing changes metabolism in people following it.

The reformulated Fuelings add a heat-treated probiotic strain, chromium picolinate and choline, which the company says help support a reduced waist, normal insulin function and normal fat metabolism (Trilivy, n.d.-c). The waist claim rests on a 3-month trial of daily capsules of the strain, not of Fuelings (Pedret et al., 2019), and the searches did not identify a study of the reformulated products themselves. A proposed mechanism like these never supports a claim in section 4.

6. Risks, contraindications and myths

(select the heading to open or close this section)

Warnings from professional or regulatory bodies

The searches for this page, in medical literature databases, did not identify a warning about this program from a medical or dietetics body; they did not cover every regulator, state attorney general or court. The Federal Trade Commission's own records describe one enforcement case. In 2012 the company's subsidiary Jason Pharmaceuticals, Inc., which sold Medifast-brand meal replacements, agreed to pay a $3.7 million civil penalty to settle commission charges that advertisements for Medifast programs, whose most advertised plan was the 5 and 1, made unsupported claims that users would lose 2 to 5 pounds a week and presented endorsers' results as typical, in violation of a 1992 commission order (Federal Trade Commission, 2012a, 2012b). The commission states that the settlement is not an admission of a violation. The case concerned advertising claims; it is not evidence that the products harmed anyone.

The company's current annual report says the resulting consent decree still requires certain procedures and disclosures in its advertising (Medifast, Inc., 2026a). The same report says that the commission's 2024 staff report on multi-level marketing income disclosures included OPTAVIA's statement among the 70 it reviewed, that the report did not indicate an investigation of any company, and that the commission is considering rules on earnings claims by multi-level marketing companies (Medifast, Inc., 2026a). The staff findings describe the 70 statements as a group; this page did not open the staff report and draws no conclusion about this company's statement from it.

The company's own disclaimer is the most detailed caution found. It warns that "Rapid weight loss may cause gallstones or gallbladder disease, temporary hair thinning, or muscle loss in some people," that some people feel dizzy, lightheaded, headachy or tired or have digestive upset while adjusting, and that muscle cramps, tingling, numbness, confusion or a rapid or irregular heartbeat call for immediate medical attention (Trilivy, n.d.-f).

Nutrient gaps

Fuelings are fortified; the company says its Fuelings contain 24 vitamins and minerals (Medifast, Inc., 2026a), and in one trial the company's plan was described as needing no added multivitamin because of that fortification (Davis et al., 2010). On the Reset plan, fruit, dairy foods and whole grains do not appear in the self-made meal (Trilivy, n.d.-m), so what a person gets of the nutrients those foods carry depends on which Fuelings they choose. The searches for this page did not identify a study of nutrient intake on the current plans.

One nutrient has been measured. A 2014 laboratory analysis of a week of products from 3 commercial weight-loss programs found that the Medifast items tested supplied about 70 micrograms of iodine a day, below the 150 micrograms recommended for adults who are not pregnant or breastfeeding (Kuriti et al., 2014). Products change, and the current vanilla shake lists potassium iodide among its added minerals (Trilivy, n.d.-c); this page did not find how much iodine the current products supply. Whether a particular person's intake meets their needs, especially in pregnancy, for a teenager or with a medical condition, is a question for a registered dietitian.

Who should not follow it without medical supervision

The company's own disclaimer is the clearest list. It says not to use any of its plans while pregnant or under age 13; says the main plan is not appropriate for teenagers, sedentary adults 65 and older, nursing mothers, people with gout, people with type 1 diabetes, or people who exercise more than 45 minutes a day or at high intensity; and asks anyone who has or has had heart disease, diabetes, cancer, thyroid, liver or kidney disease, an eating disorder such as anorexia or bulimia, or any condition that weight loss may affect, to be cleared by a healthcare provider before starting (Trilivy, n.d.-f).

Anyone taking insulin, a sulfonylurea or another medicine that can cause low blood sugar needs the prescriber involved before the plan starts (National Institute of Diabetes and Digestive and Kidney Diseases, n.d.-a). A person with kidney disease needs the kidney care team involved, because needs depend on the stage, lab results and dialysis. More generally, the main plan's calorie level is in the range England's national clinical guideline calls a low-energy diet, which it advises using only with clinical support, for a limited time and after a review of medicines (National Institute for Health and Care Excellence, 2025). The special populations list in section 3 is built from these cautions.

Medication interactions

Insulin, sulfonylureas and meglitinides can cause low blood sugar, and eating too little carbohydrate or skipping or delaying meals makes it more likely (National Institute of Diabetes and Digestive and Kidney Diseases, n.d.-a). The company lists warfarin, lithium, diuretics and medicines for weight loss, diabetes, high blood pressure or thyroid conditions as ones to discuss with a healthcare provider before starting, and adds that changing how much water a person drinks can affect certain conditions and medicines (Trilivy, n.d.-f). For a client taking a GLP-1 medication, the company sells a plan of its own (Medifast, Inc., 2026a); how any eating plan fits with that medicine is the prescriber's decision. A coach never adjusts medication. The point of knowing these is to know when the client should talk with the prescriber before starting.

Signs it is going wrong

Physical signs that call for the client's care plan, a clinician or emergency help include shakiness, sweating or confusion in someone taking diabetes medicine, which may be low blood sugar happening now and is treated first under the person's own plan, with emergency help if symptoms are severe or the person cannot manage the episode, and the prescriber told afterward (National Institute of Diabetes and Digestive and Kidney Diseases, n.d.-a).

They also include the symptoms the company itself names for immediate attention, muscle cramps, tingling, numbness, confusion, or a rapid or irregular heartbeat (Trilivy, n.d.-f); abdominal pain lasting several hours, vomiting, fever or yellowing of the skin or eyes, which can point to a gallstone complication (National Institute of Diabetes and Digestive and Kidney Diseases, n.d.-b); dizziness, fatigue that does not settle, or hair thinning, which the company also names (Trilivy, n.d.-f); and weight lost without meaning to, outside the plan.

Eating behaviors are a separate matter. Restarting the plan again and again with distress, staying on the most restrictive phase much longer than intended, cutting the self-made meal, weighing many times a day, or withdrawing from meals with others can each have ordinary explanations, such as a work schedule, food access, cultural practice, household preferences or a clinician's plan, and on its own none is a diagnosis. The coach asks what the behavior is for, whether it causes distress, whether it is narrowing what the person eats, and whether it is getting in the way of daily life. A real concern goes through the coach’s own referral process, or to the client's clinician under an existing care plan.

Myths and where they came from

Myth: "The research proves that having a coach makes you lose 10 times as much."

Where it came from: the company's pages, which cite the 2019 trial (Trilivy, n.d.-b, n.d.-e). What is true: the trial compared the coached plan with a self-directed food-based diet that differed in food, calories and free products as well as coaching; the group that used the company's products without a coach lost almost as much as the coached group; and the authors wrote that conclusions about the separate effects of the plans and the support were not possible (Arterburn et al., 2019).

Myth: "Nine out of 10 people have metabolic dysfunction, and this plan reverses it."

Where it came from: the company's pages and annual report, citing a national study (Trilivy, n.d.-e, n.d.-g; Medifast, Inc., 2026a). What is true: that study found 6.8 percent of U.S. adults had optimal levels on all 5 cardiometabolic measures it used, which is not the same as most people having a dysfunction (O'Hearn et al., 2022), and the trial the company cites for the plan did not measure metabolic dysfunction (Arterburn et al., 2019).

Myth: "My Optavia coach is a health coach, so it is the same as working with a certified coach."

Where it came from: the shared word coach, and the program's earlier name for its sellers, Health Coaches (Medifast, Inc., 2017). What is true: the company's coaches complete the company's own training and exam and are paid through its compensation plan (Medifast, Inc., 2026a; Trilivy, n.d.-e), while National Board certification requires an approved training program, 50 logged coaching sessions and a board examination, and its scope excludes creating meal plans (National Board for Health & Wellness Coaching, n.d.-b, n.d.-c).

Myth: "It started with doctors, so it is a medically supervised program."

Where it came from: the company's physician-founded history and its earlier sales through doctors' offices (Trilivy, n.d.-a; Medifast, Inc., 2017). What is true: the company states that it does not engage physicians or nurses to monitor its clients and that it and its coaches do not provide medical services (Medifast, Inc., 2026a; Trilivy, n.d.-k). Supervision comes from the client's own clinicians, which is why the company tells clients to consult them.

7. Key terms

Fueling

The company's name for its packaged, portion-controlled meal replacements, such as shakes, bars, soups and puddings.

Lean & Green meal

The self-made meal on the company's plans: 5 to 7 ounces of lean protein, up to 2 servings of healthy fat and 3 servings of non-starchy vegetables.

Reset 5 & 1 Plan

The company's main weight-loss plan, earlier called the Optimal Weight 5 & 1 Plan: 5 Fuelings and 1 Lean & Green meal a day, at about 800 to 1,000 calories in its trial.

Refine and Renew

The company's names for the phases after weight loss, which add self-made meals, snacks and other foods back.

Premier+

The company's autoship program, which ships products every 28 days at a discount unless the client changes the order.

Independent coach

In this program, a person who buys the company's coach kit, completes its training, supports clients and is paid through its compensation plan; not a health professional credential.

Income disclosure statement

A company's published summary of what its sellers earned in a year, by earnings range.

National Board Certified Health and Wellness Coach

A coach who has completed an approved training program and coaching hours and passed the national board examination.

Meal replacement

A packaged product with a set amount of calories and nutrients, eaten in place of a meal.

Low-energy diet

A diet of about 800 to 1,200 calories a day, in the terms England's national clinical guideline uses; under 800 is a very-low-energy diet.

Modified intention-to-treat analysis

An analysis that keeps people in the group they were assigned to, limited to those with at least one measurement after the start.

Completers analysis

An analysis that reports results only for people who finished a study, which can make a program look better if those who struggled left.

Visceral fat

Fat stored around the internal organs in the abdomen.

GLP-1 medication

A class of prescription medicines used for type 2 diabetes and weight management.

Direct selling

Selling products through independent contractors who reach customers personally rather than through stores.

8. Review questions

1. Describe a day on the Reset 5 & 1 Plan, what it costs each month at the company's listed prices, and who earns money when a client follows it.
2. Drawing on section 4: what did the 2019 trial compare, for how long and in whom, and why can it not show how much of the result came from the coaching?
3. A client who takes a sulfonylurea for type 2 diabetes tells you her neighbor, an Optavia coach, is about to sign her up for the 5 and 1 plan. What does the coach do, and where are the referral lines?
4. Explain the difference between an Optavia coach and a National Board Certified Health and Wellness Coach in training, scope and how each is paid, in words you could use with a client without criticizing either.
5. Drawing on sections 4 and 6: where does the claim that 9 out of 10 adults have metabolic dysfunction come from, and what did the study it cites measure?

9. References

Arterburn, L. M., Coleman, C. D., Kiel, J., Kelley, K., Mantilla, L., Frye, N., Sanoshy, K., & Cook, C. M. (2019). Randomized controlled trial assessing two commercial weight loss programs in adults with overweight or obesity. Obesity Science & Practice, 5(1), 3-14. https://doi.org/10.1002/osp4.312

Beavers, K. M., Nesbit, B. A., Kiel, J. R., Sheedy, J. L., Arterburn, L. M., Collins, A. E., Ford, S. A., Henderson, R. M., Coleman, C. D., & Beavers, D. P. (2019). Effect of an energy-restricted, nutritionally complete, higher protein meal plan on body composition and mobility in older adults with obesity: A randomized controlled trial. The Journals of Gerontology: Series A, 74(6), 929-935. https://doi.org/10.1093/gerona/gly146

Cheskin, L. J., Mitchell, A. M., Jhaveri, A. D., Mitola, A. H., Davis, L. M., Lewis, R. A., Yep, M. A., & Lycan, T. W. (2008). Efficacy of meal replacements versus a standard food-based diet for weight loss in type 2 diabetes: A controlled clinical trial. The Diabetes Educator, 34(1), 118-127. https://doi.org/10.1177/0145721707312463

Coleman, C., Kiel, J., LaCalamita, C., Frye, N., & Provelengios, L. (2022). Healthy habits associated with successful weight loss maintenance on a commercial program: Learnings from a research survey. Food and Nutrition Sciences, 13(5), 453-462. https://doi.org/10.4236/fns.2022.135033

Coleman, C. D., Kiel, J. R., Mitola, A. H., & Arterburn, L. M. (2017). Comparative effectiveness of a portion-controlled meal replacement program for weight loss in adults with and without diabetes/high blood sugar. Nutrition & Diabetes, 7(7), Article e284. https://doi.org/10.1038/nutd.2017.32

Coleman, C. D., Kiel, J. R., Mitola, A. H., Langford, J. S., Davis, K. N., & Arterburn, L. M. (2015). Effectiveness of a Medifast meal replacement program on weight, body composition and cardiometabolic risk factors in overweight and obese adults: A multicenter systematic retrospective chart review study. Nutrition Journal, 14, Article 77. https://doi.org/10.1186/s12937-015-0062-8

Davis, L. M., Coleman, C., Kiel, J., Rampolla, J., Hutchisen, T., Ford, L., Andersen, W. S., & Hanlon-Mitola, A. (2010). Efficacy of a meal replacement diet plan compared to a food-based diet plan after a period of weight loss and weight maintenance: A randomized controlled trial. Nutrition Journal, 9, Article 11. https://doi.org/10.1186/1475-2891-9-11

Federal Trade Commission. (2012a). Jason Pharmaceuticals, Inc. ftc.gov/legal-library/browse/cases-proceedings/jason-pharmaceuticals-inc

Federal Trade Commission. (2012b, September 10). Subsidiary of diet plan marketer Medifast Inc. to pay $3.7 million to settle FTC charges [Press release]. ftc.gov/news-events/news/press-releases/2012/09/subsidiary-diet-plan-marketer-medifast-inc-pay-37-million-settle-ftc-charges

Gudzune, K. A., Doshi, R. S., Mehta, A. K., Chaudhry, Z. W., Jacobs, D. K., Vakil, R. M., Lee, C. J., Bleich, S. N., & Clark, J. M. (2015). Efficacy of commercial weight-loss programs: An updated systematic review. Annals of Internal Medicine, 162(7), 501-512. https://doi.org/10.7326/M14-2238

Johns Hopkins Bloomberg School of Public Health. (n.d.). Efficacy of 2 diet plans designed for people with type II diabetes on weight and health measures (Identifier NCT00198757). ClinicalTrials.gov. clinicaltrials.gov/study/NCT00198757

Kuriti, M., Pearce, E. N., Braverman, L. E., He, X., & Leung, A. M. (2014). Iodine content of U.S. weight-loss food. Endocrine Practice, 20(3), 232-235. https://doi.org/10.4158/EP13310.OR

Laudenslager, M., Chaudhry, Z. W., Rajagopal, S., Clynes, S., & Gudzune, K. A. (2021). Commercial weight loss programs in the management of obesity: An update. Current Obesity Reports, 10(2), 90-99. https://doi.org/10.1007/s13679-021-00428-y

Lichtenstein, A. H., Khera, A., Anderson, C. A. M., Appel, L. J., DeSilva, D. M., Gardner, C., Hu, F. B., Jones, D. W., Petersen, K. S., & American Heart Association. (2026). 2026 dietary guidance to improve cardiovascular health: A scientific statement from the American Heart Association. Circulation, 153(18), e1285-e1295. https://doi.org/10.1161/CIR.0000000000001435

Medifast, Inc. (2017). Form 10-K: Annual report for the fiscal year ended December 31, 2016. U.S. Securities and Exchange Commission. sec.gov/Archives/edgar/data/910329/000114420417015143/v461286_10k.htm

Medifast, Inc. (2018). Form 10-K: Annual report for the fiscal year ended December 31, 2017. U.S. Securities and Exchange Commission. sec.gov/Archives/edgar/data/910329/000114420418015288/tv487131_10k.htm

Medifast, Inc. (2026a). Form 10-K: Annual report for the fiscal year ended December 31, 2025. U.S. Securities and Exchange Commission. sec.gov/Archives/edgar/data/910329/000162828026008656/med-20251231.htm

Medifast, Inc. (2026b, March 20). Medifast announces cooperation agreement with Steamboat Capital [Press release]. Exhibit 99.1 to Form 8-K, U.S. Securities and Exchange Commission. sec.gov/Archives/edgar/data/910329/000162828026019983/medreleasesteamboat.htm

Medifast, Inc. (2026c, August 3). Medifast announces second quarter 2026 financial results [Press release]. Exhibit 99.1 to Form 8-K, U.S. Securities and Exchange Commission. sec.gov/Archives/edgar/data/910329/000162828026051845/medq22026earningsrelease.htm

Medifast, Inc. (2026d, July 17). Medifast enters a new era: Introducing Trilivy, a science-backed metabolic health system [Press release]. Exhibit 99.1 to Form 8-K, U.S. Securities and Exchange Commission. sec.gov/Archives/edgar/data/910329/000162828026048574/rebrandpressrelease.htm

Miller, A. J., Coleman, C. D., Kiel, J. R., Beavers, K. M., & Jonnalagadda, S. S. (2026). Structured higher protein meal replacement plans for weight loss and metabolic health: A qualitative narrative evidence review of Medifast interventions. Obesity Pillars, 18, Article 100265. https://doi.org/10.1016/j.obpill.2026.100265

Moldovan, C. P., Weldon, A. J., Daher, N. S., Schneider, L. E., Bellinger, D. L., Berk, L. S., Hermé, A. C., Aréchiga, A. L., Davis, W. L., & Peters, W. R. (2016). Effects of a meal replacement system alone or in combination with phentermine on weight loss and food cravings. Obesity, 24(11), 2344-2350. https://doi.org/10.1002/oby.21649

National Board for Health & Wellness Coaching. (n.d.-a). Exam eligibility requirements. nbhwc.org/exam-eligibility-requirements

National Board for Health & Wellness Coaching. (n.d.-b). Get board certified. nbhwc.org/get-board-certified

National Board for Health & Wellness Coaching. (n.d.-c). Scope of practice. nbhwc.org/scope-of-practice

National Board for Health & Wellness Coaching. (2025). Code of ethics and professional conduct. nbhwc.org/wp-content/uploads/2025/11/NBHWC-Code-of-Ethics-and-Professional-Conduct-1.pdf

National Institute for Health and Care Excellence. (2025). Overweight and obesity management (NICE Guideline No. NG246; last updated January 8, 2026). nice.org.uk/guidance/ng246/chapter/Physical-activity-and-diet

National Institute of Diabetes and Digestive and Kidney Diseases. (n.d.-a). Low blood glucose (hypoglycemia). niddk.nih.gov/health-information/diabetes/overview/preventing-problems/low-blood-glucose-hypoglycemia

National Institute of Diabetes and Digestive and Kidney Diseases. (n.d.-b). Symptoms & causes of gallstones. niddk.nih.gov/health-information/digestive-diseases/gallstones/symptoms-causes

Neff, R. A., Ramsing, R. J., & Kim, B. F. (2023). Commercial weight-loss diets, greenhouse gas emissions and freshwater consumption. Journal of Human Nutrition and Dietetics, 36(6), 2268-2279. https://doi.org/10.1111/jhn.13248

O'Hearn, M., Lauren, B. N., Wong, J. B., Kim, D. D., & Mozaffarian, D. (2022). Trends and disparities in cardiometabolic health among U.S. adults, 1999-2018. Journal of the American College of Cardiology, 80(2), 138-151. https://doi.org/10.1016/j.jacc.2022.04.046

Pedret, A., Valls, R. M., Calderón-Pérez, L., Llauradó, E., Companys, J., Pla-Pagà, L., Moragas, A., Martín-Luján, F., Ortega, Y., Giralt, M., Caimari, A., Chenoll, E., Genovés, S., Martorell, P., Codoñer, F. M., Ramón, D., Arola, L., & Solà, R. (2019). Effects of daily consumption of the probiotic Bifidobacterium animalis subsp. lactis CECT 8145 on anthropometric adiposity biomarkers in abdominally obese subjects: A randomized controlled trial. International Journal of Obesity, 43(9), 1863-1868. https://doi.org/10.1038/s41366-018-0220-0

Semnani-Azad, Z., Khan, T. A., Chiavaroli, L., Chen, V., Bhatt, H. A., Chen, A., Chiang, N., Oguntala, J., Kabisch, S., Lau, D. C., Wharton, S., Sharma, A. M., Harris, L., Leiter, L. A., Hill, J. O., Hu, F. B., Lean, M. E., Kahleová, H., Rahelic, D., . . . Sievenpiper, J. L. (2025). Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: Systematic review and network meta-analysis of randomised clinical trials. BMJ, 389, Article e082007. https://doi.org/10.1136/bmj-2024-082007

Shikany, J. M., Thomas, A. S., Beasley, T. M., Lewis, C. E., & Allison, D. B. (2013). Randomized controlled trial of the Medifast 5 & 1 Plan for weight loss. International Journal of Obesity, 37(12), 1571-1578. https://doi.org/10.1038/ijo.2013.43

Trilivy. (n.d.-a). About Trilivy Health. trilivyhealth.com/us/en/about-us

Trilivy. (n.d.-b). Become a Trilivy coach. trilivyhealth.com/us/en/become-a-coach

Trilivy. (n.d.-c). Classic creamy vanilla shake mix. trilivyhealth.com/us/en/classic-creamy-vanilla-shake-mix/p/78270-reset-van-shake-bx

Trilivy. (n.d.-d). How the Trilivy program works: Reset, Refine, Renew. trilivyhealth.com/us/en/program-overview

Trilivy. (n.d.-e). Is Trilivy legitimate? A fact-based look at the evidence. trilivyhealth.com/us/en/is-trilivy-legitimate-a-fact-based-look-at-the-evidence

Trilivy. (n.d.-f). Medical disclaimer. trilivyhealth.com/us/en/medical-disclaimer

Trilivy. (n.d.-g). Optavia is now Trilivy. trilivyhealth.com/us/en/optavia-is-now-trilivy

Trilivy. (n.d.-h). Optavia reviews by doctors, dietitians, and clinical researchers: A fact-based look. trilivyhealth.com/us/en/reviews-by-doctors-dietitians-and-clinical-researchers-a-fact-based-look

Trilivy. (n.d.-i). Reset 5 & 1 Plan (kit). trilivyhealth.com/us/en/reset-5-1-plan/p/78560TrilivyReset51PlanKit

Trilivy. (n.d.-j). Reset 5 & 1 Plan: Clinically proven weight loss. trilivyhealth.com/us/en/5-1-plan

Trilivy. (n.d.-k). Reset phase: Reverse metabolic dysfunction. trilivyhealth.com/us/en/reset

Trilivy. (n.d.-l). Save with Trilivy Premier+. trilivyhealth.com/us/en/trilivy-premier

Trilivy. (n.d.-m). Trilivy Refine plan: Maintenance and GLP-1 transition. trilivyhealth.com/us/en/refine-plan

Trilivy. (2026). Trilivy 2025 U.S. income disclosure statement. media.trilivyhealth.com/pdf/learn/Trilivy-IDS.pdf

Vakil, R. M., Chaudhry, Z. W., Doshi, R. S., Clark, J. M., & Gudzune, K. A. (2017). Commercial programs' online weight-loss claims compared to results from randomized controlled trials. Obesity, 25(11), 1885-1893. https://doi.org/10.1002/oby.21959

Evidence rating and review record

Each row identifies the method, source, outcome or recommendation, and comparison being rated. Ratings from different tools are not interchangeable. The source is either a named published review or this page's own judgment. The rating in the banner is for this diet's main claimed outcome or recommendation, and the banner names the tool that produced it. A high rating means the research is solid; it does not mean the diet is right for everyone, and it does not mean a coach should recommend it.

The rated outcomes on this page use GRADE, the same 4-level scale as the clinical guidelines you will meet in practice. High means further research is very unlikely to change the conclusion. Moderate means further research may change it. Low means further research is likely to change it. Very low means the conclusion is uncertain. GRADE rates each outcome separately, so a diet can be high for one outcome and very low for another. A row marked Not rated is an abstention, not a certainty level: where no study addresses a question, there is nothing to rate.

For Optavia, every row is this page's own judgment, because the searches did not identify a published review that rated the program. Three rows are rated and 6 are not. The banner reflects the first row, the measured outcome the company's own trial was designed around. Most of the research was funded by the company, and much of it was written by its employees. Funding alone is not counted as a reason to lower a rating; each row says whether it could have biased that result, for example through how missing data were handled, and the absence of independent, longer trials matters in its own right.

For differences in measured weight between groups, this page treats 2 kilograms as the smallest difference that matters when judging how precise a result is, the minimally important difference a 2025 network meta-analysis of intermittent fasting trials used for body weight (Semnani-Azad et al., 2025). That threshold is a way of reading a trial's result, not a goal for anyone. Where a paper reports no interval for the difference between groups, the row gives an approximate one that this page calculated, and says so. A row marked Not rated does not mean the program has no effect or no risk on that outcome.

On a narrow screen, scroll the table sideways to see every column.

Evidence ratings, their sources and reasons

Outcome	Certainty	Who rated it, and for which comparison	Why it is rated this way
Body weight at 16 weeks, as measured (the banner rating)	Moderate	GRADE, this page's own judgment, from one trial (Arterburn et al., 2019). Question rated: the program as currently sold, the 5 & 1 plan with an independent Optavia coach and products the client pays for, against a self-directed reduced-calorie diet, in adults aged 18 to 65 with a body mass index of 27 to 42 and without medicated diabetes, measured weight change at 16 weeks. Evidence: the 2016 version of the plan with 23 scheduled telephone calls, against a self-directed MyPlate diet, in 198 adults.	Randomized evidence starts at high. Risk of bias not lowered: the sequence was computer-generated by an independent statistician and concealed in sealed envelopes; weight was measured on a medical scale after a fast; 92 percent were assessed at 16 weeks; results were similar in the main, full and completers analyses; the trial was registered before it began, with this outcome as its primary outcome. Participants and staff knew the assignments, and the company funded the trial and paid 4 authors. That could bias the result if the comparison group, knowing it had the least support, tried less hard, but a fasting scale weight is hard to influence and the comparison group's small loss resembles self-directed groups in other trials, so this is not judged serious. Inconsistency cannot be assessed with one trial and is not a deduction. Lowered 1 level for indirectness, because the question is the program as sold: the trial's coaches were research assistants without coaching experience, while the program's coaches are independent sellers with every level of experience, paid through the compensation plan; products were free and participants were paid for visits, while clients pay about $384 to $480 for 28 days; and the Fuelings were reformulated in 2026. For the trial's own 2016 package, nothing would lower the rating. Imprecision not lowered: the difference was about 5.0 kilograms (approximate 95 percent interval 3.1 to 6.9, calculated by this page from the paper's group means and standard errors), wholly above the 2-kilogram threshold. Publication bias not lowered: registered with posted results, though one trial cannot be tested. No reason to raise the rating. Weight is a measurement here, not a goal.
Body weight at 40 weeks, as measured: the 5 & 1 meal plan without an Optavia coach	Very low	GRADE, this page's own judgment, from one trial (Davis et al., 2010). Comparison: the 5 & 1 meal plan as then sold, with free products, against a food-based diet of about the same calories, both with dietitian visits during 16 weeks of weight loss and then 24 weeks of maintenance, in 90 adults with a body mass index of 30 to 50, measured weight at 40 weeks.	Randomized evidence starts at high. Lowered 2 levels for risk of bias: results are reported only for people who stayed, and 26 of 45 in the meal-plan group and 20 of 45 in the food-based group were measured at 40 weeks, so about half the data are missing and the groups lost different shares; participants knew their diet, and company employees ran and wrote the trial, choosing a completers-only report. Inconsistency cannot be assessed with one trial. Indirectness not lowered for this question, the meal plan as then sold without an Optavia coach; it does not describe the current products. Lowered 1 level for imprecision: among completers the meal-plan group was about 3.2 kilograms further below its starting weight, with an approximate 95 percent interval from 1.9 kilograms in favor of the food-based diet to 8.3 in favor of the meal plan (calculated by this page from the paper's means and standard deviations), which includes no difference and the 2-kilogram threshold. Publication bias not lowered: registered, one trial. Three levels below high is Very low.
Body weight at 52 weeks, as measured: the 5 & 1 meal plan without an Optavia coach	Moderate, provisional	GRADE, this page's own judgment, from one trial (Shikany et al., 2013). Comparison: the 5 & 1 plan as then sold directly by phone and online, with free products and the company's online support, against a 1,000-calorie food-based diet, in 120 adults aged 19 to 65 with a body mass index of 35 to 50, measured weight at 52 weeks (26 of weight loss, 26 of maintenance). Provisional because the published article was not opened; the abstract and the authors' accepted manuscript were read, and the numbers used are the abstract's.	Randomized evidence starts at high. Risk of bias not lowered: the manuscript describes sequentially numbered, sealed envelopes prepared by university statisticians, and the abstract reports an intention-to-treat analysis of all 120, with 50 of 60 and 45 of 60 completing on their assigned plan. Participants knew their diet, the authors note that being assigned to the less wanted diet could have affected how closely people followed it, the company supplied the products, and one author had consulted for it; for a measured weight in a university-run trial this is not judged serious, but the judgment rests on the manuscript and needs the published methods. Inconsistency cannot be assessed with one trial. Indirectness not lowered for this question; the current products differ. Lowered 1 level for imprecision: the race-adjusted difference was 2.8 kilograms (4.7 against 1.9), and the approximate 95 percent interval this page back-calculated from the abstract's P value of 0.0004 is 1.2 to 4.4 kilograms, which crosses the 2-kilogram threshold. Publication bias not lowered: registered, one trial. To be rechecked against the published article.
Body weight beyond 1 year on the coached program or the 5 & 1 plan	Not rated	This page's own judgment. Comparison: the program against any other approach, after 52 weeks.	The searches did not identify a trial of the coached program or the 5 & 1 plan lasting longer than 52 weeks. A trial of the company's diabetes products reported weight to 86 weeks in its abstract (Cheskin et al., 2008), but it tested a different product line, at 75 percent of predicted energy needs, in adults with type 2 diabetes, and its abstract does not say whether participants kept using the products through the maintenance year; following people to 86 weeks is not the same as 86 weeks on the plan. It is not transferred, and only its abstract was read.
The effect of the coaching itself	Not rated	This page's own judgment. Comparison: the same meal plan with and without an Optavia coach.	The searches did not identify a trial comparing the same plan with and without coaching. The 2019 trial's 2 company groups differed in plan and calories as well as support, and its authors state that conclusions about their separate effects were not possible; the link between calls completed and weight lost is within-group and observational (Arterburn et al., 2019).
Blood sugar control in type 2 diabetes	Not rated	This page's own judgment. Comparison: the program against usual care or another diet in adults with type 2 diabetes.	The coached trial excluded people with medicated diabetes (Arterburn et al., 2019). The one trial of the company's diabetes products was read as an abstract, which does not report blood sugar results (Cheskin et al., 2008).
Heart attacks, strokes, cancer and death	Not rated	This page's own judgment. Comparison: the program against any comparison.	The searches did not identify a trial or cohort study that measured these outcomes; the trials found were 12 to 86 weeks long and too small to count such events, so they show neither benefit nor harm on them.
Disordered eating during or after the program	Not rated	This page's own judgment. Comparison: people on the program against people not on it, with and without a history of disordered eating.	The searches did not identify a study that measured it, and the coached trial excluded people with a history of eating disorders. The company's request that such clients be cleared first is a company safety statement, not a research finding (Trilivy, n.d.-f).
Gallstones and other harms	Not rated	This page's own judgment. Comparison: the program against any comparison.	In the 2019 trial, the adverse events judged at least possibly related to the diets were mild or moderate and mostly digestive, and none of its 4 serious adverse events was judged related; the 40-week trial reported no significant adverse events (Arterburn et al., 2019; Davis et al., 2010). In the phentermine trial, one case of high blood pressure was managed by tapering the medicine, an event in a trial that added a drug, not evidence about the meal plan alone (Moldovan et al., 2016). These trials were too small and short to estimate rates of uncommon harms such as gallstones, and Not rated does not mean that harms do not occur. The company's own warning about gallstones and other effects of rapid weight loss is reported in section 6 as the company's statement (Trilivy, n.d.-f).

How this archive talks about weight. This page reports what studies measured, including body weight, and does not treat weight change as a goal or as a measure of a diet's success. Weight a person loses without meaning to can be a sign of a health problem, and where it is, the page names it as a reason to see a clinician. People are described the way the study described them.

Last reviewed: Reviewed and approved by James Peth, MS, MPH, PhD, on October 11, 2026, after a combined final review of the fourth batch of 5 archive pages, the commercial programs, the repairs it asked for and a targeted recheck. Written October 11, 2026. The judgments in the table are this page's own, assigned from the evidence. Some sources could be read only as abstracts or author manuscripts, and the page says so where each is used. Company prices and terms are a snapshot from the company's own pages on October 11, 2026, and can change.

What changed: The main plan is now described as a low-energy diet, with the clinical guidance that applies, wherever safety comes up. The 16-week rating now names the program as sold as its question; the longer-term rating is split into separate 40-week and 52-week rows, each with its own reasons and a stated 2-kilogram threshold. The phentermine trial is described from its full article. The 2012 Federal Trade Commission settlement is described from the commission's own records. Company figures that the published trial does not report are described as not verifiable rather than as contradicted. Kidney care, coaches' earnings and the two coaching roles are described more exactly.

Updated October 21, 2026: The 2015 review's correction notice was read for this archive, and the evidence paragraph and the highlighted-study row now say what it covers. No rating changed.

Next scheduled review: Each year, because the company renamed the program in July 2026 and changes its plans, products and prices. Pages built on annual guidance are rechecked each year.

---

Diet Reference Archive | One James

Prepared by James Peth, MS, MPH, PhD

© 2026–2027 One James. All rights reserved.

This page is for education and coaching practice. It is not medical or dietary advice.