Time-Restricted Eating

Diet Reference Archive: an eating pattern defined by timing

Time-Restricted Eating

A way of eating in which all food and drink with calories is eaten within the same window of hours each day, often 8 to 10 hours, with no calories for the rest of the day. It is promoted mainly for weight loss and blood sugar control, and sometimes for keeping meals in step with the body clock.

Family: Fasting and meal timing Promoted by: circadian research groups and app makers First appeared: in research, the 2010s CINeMA, a GRADE-based method: Moderate for measured body weight changing about as much with time-restricted eating as with daily calorie restriction, in adults mostly with overweight or obesity in trials of 3 to 52 weeks; published review (Semnani-Azad et al., 2025)

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. Review questions 2 and 4 draw on sections 4 and 6. Back to the Diet Reference Archive index.

In brief

What is it? Time-restricted eating means eating all of the day's food within a set number of hours, the same hours each day, and having nothing with calories outside them. The best-known version, 16:8, is an 8-hour eating window, such as noon to 8 p.m., and 16 hours without food. Studies have used windows from about 4 to 12 hours, placed early, late or wherever the person chooses. It is one member of the intermittent fasting family, and the Intermittent Fasting page covers the other members.

Does it work? In randomized trials, mostly in adults with overweight or obesity and mostly lasting weeks to a year, people following an eating window lost about as much weight as people asked to eat a little less every day. A large 2025 review rated that finding moderate in certainty. Compared with making no change to when they ate, people lost a little weight, about 1.7 kilograms on average, an amount the same review called trivial. For long-term blood sugar, the review did not detect a difference against either comparison. One 2026 review found that early windows did a little better than late ones over about 2 months, and others found no clear difference. Whether timing adds anything beyond eating less is not settled, and no trial identified for this page measured heart attacks, strokes or length of life.

Is it safe? For most healthy adults in the trials, side effects were mild, such as hunger in the evening, headache, dizziness and constipation. The main cautions are for people taking insulin or a sulfonylurea for diabetes, whose blood sugar can drop too low when meals move, and for people with a history of disordered eating, for whom a rule about when eating is allowed can become harmful. Some trials also found a small loss of lean mass along with fat.

Who should not do it without talking to a doctor or dietitian first? Anyone taking insulin, a sulfonylurea or another medicine that lowers blood sugar; anyone with type 1 diabetes; anyone who is pregnant, breastfeeding or trying to become pregnant; anyone with a history of an eating disorder; children and teenagers; older adults who are frail or losing muscle; anyone with chronic kidney disease; and anyone taking medicine for blood pressure or a blood thinner who plans a large change in how they eat.

Related pages: Intermittent Fasting, Mediterranean Diet, Ketogenic Diet, Intuitive Eating. Full list on the archive index.

1. Overview

What you do

Time-restricted eating sets a daily window for eating and leaves the rest of the 24 hours without calories. Inside the window, many research versions set no limit on how much or what a person eats; outside it, the person has water and drinks without calories (Lowe et al., 2020; S. Lin et al., 2023). The window is meant to be the same every day, or nearly every day. Trials have asked people to keep it on at least 6 days a week (Jamshed et al., 2022), on at least 5 days a week (Sujan et al., 2025), or simply daily (Lowe et al., 2020).

Three things define a particular version, and a client who says "I do intermittent fasting" may mean any combination of them.

• How long the window is. The common 16:8 pattern is an 8-hour window and 16 hours without food. Definitions vary widely. A 2023 federal research workshop described time-restricted eating as a consistent window of 8 to 10 hours or less (Dashti et al., 2025). Trialists have defined it as 10 hours or less (Jamshed et al., 2022). Reviews have accepted windows of up to 12 hours (Viple et al., 2026; Y.-E. Chen et al., 2026), and the American Diabetes Association's 2026 standards describe windows of 8 to 15 hours (American Diabetes Association Professional Practice Committee for Diabetes, 2026). One closely controlled study used a window of 6 hours (Sutton et al., 2018), and the trials in one 2026 review used windows of 4 to 10 hours (Viple et al., 2026).
• When the window falls. An early window ends in the afternoon, such as 8 a.m. to 4 p.m. (Liu et al., 2022); a late window starts around midday, such as noon to 8 p.m. (Lowe et al., 2020); and a self-selected window is chosen by the person, sometimes with a latest finishing time, such as 7 p.m. (Parr et al., 2026). Researchers do not draw these lines in the same place, which section 4 explains.
• Whether calories are also limited. Some trials combined the window with a calorie target for everyone, so the window was the main planned difference between groups (Liu et al., 2022; Jamshed et al., 2022). Others set the window alone and let people eat freely inside it (S. Lin et al., 2023). The results of these two designs answer different questions.

What you do not do

The rule is about the clock. A person following an eating window does not eat or drink anything with calories outside it. What counts as breaking the window is not standardized. In one trial, the stated fasting rule allowed water and black coffee or tea, and the corrected methods also describe an initial exception for people easing into the fast (Lowe et al., 2020). Another allowed water, black tea, coffee and up to 2 diet sodas a day during the fast (S. Lin et al., 2023). A third counted every food or drink, including coffee, tea and diet drinks, as an eating occasion when it measured the window, leaving out only water and medications (Oldenburg et al., 2025). Medicines are taken as prescribed; a window is never a reason to move a dose, and section 6 explains why that matters most for diabetes medicines.

Most versions name no foods to avoid, and nothing in the pattern requires cutting out a food group. Food quality is a separate matter, which is why the American Diabetes Association's standards note that the principles of healthy eating still apply during the hours when people eat (American Diabetes Association Professional Practice Committee for Diabetes, 2026).

Where it came from

Time-restricted eating grew out of laboratory work on the body clock. In a 2012 study at the Salk Institute, mice fed a high-fat diet for only 8 hours a day ate as many calories as mice with food available around the clock, yet they were protected against obesity, high insulin, fatty liver and inflammation (Hatori et al., 2012). The researchers argued that eating at all hours disrupted the normal daily cycle of feeding and fasting. Animal findings like these are a reason to study a pattern in people, not evidence about people.

The same group then asked how people eat in daily life. Using a phone app that recorded every food and drink, they found in 156 healthy adults that eating was spread across most waking hours, that less than a quarter of calories came before noon, and that half the group ate across more than 14.75 hours a day. In a small pilot, 8 people with overweight who normally ate across more than 14 hours were asked to eat within 10 to 11 hours for 16 weeks; they lost weight and reported more energy and better sleep, with no comparison group (Gill & Panda, 2015). Because that pilot had no comparison group, the randomized trials in section 4 carry far more weight.

As a popular pattern, time-restricted eating spread alongside intermittent fasting in general; the Intermittent Fasting page describes that history. Names such as 16:8 and 18:6 give the hours of fasting first and the hours of eating second.

What it claims to do

The central claim is weight loss without counting calories. Researchers who study the pattern describe its appeal as letting people "watch the clock" instead of monitoring calories (S. Lin et al., 2023). A second, more specific claim is that eating in step with the body clock improves metabolism beyond whatever weight a person loses. The 2023 federal workshop report describes eating time as a cue that sets the clocks in the body's organs and states that limiting the window and shifting it earlier in the day "may be an effective strategy to improve health" (Dashti et al., 2025).

Clients also bring claims that the pattern resets metabolism, burns fat in a special way, improves sleep and energy, and slows aging; these are offered from observation, not from a study. Section 4 reports what the trials show for weight, blood sugar and other measures, section 5 separates what has been shown in people from what has been proposed, and section 6 takes the myths one at a time.

What it gets right

Two things hold up. The first is that a simple rule can help some people eat less without tracking. In a 12-month trial in Chicago, people asked only to eat between noon and 8 p.m. reported eating about 425 fewer calories a day, close to the 405 fewer reported by people counting calories, and their weight change did not differ significantly (S. Lin et al., 2023). In a review of 13 qualitative studies, men more often named routine and a planned day as things that helped, and women more often named food cravings and emotional eating as things that got in the way (Fernández-Rodríguez et al., 2026). Ease is one consideration alongside a person's needs and clinical circumstances.

The second is that the pattern is flexible. The American Diabetes Association's standards note that shortening the eating window "can be adapted to any eating pattern" (American Diabetes Association Professional Practice Committee for Diabetes, 2026). A window can hold Mediterranean-style meals, the foods of a person's culture, or whatever they already eat. In one Spanish trial, all groups, including those with an eating window, received education about the Mediterranean diet (Dote-Montero et al., 2025). The pattern says nothing about food quality, so the Mediterranean Diet page and the Harvard Healthy Eating Plate page remain the places to look for what goes inside the window.

How clients describe it, and what it gets confused with

Clients say "I do 16:8," "I stop eating at 7," "I don't eat before noon," "I'm on an 18:6," "my window is 10 to 6," or "I skip breakfast now." These phrases are offered from observation, not from a study. A client who skips breakfast may be following a plan, working an early shift, or simply not hungry in the morning; the coach asks before assuming.

Time-restricted eating is often confused with 4 other things. The 5:2 pattern and alternate-day fasting restrict calories on certain days rather than hours on every day; both are on the Intermittent Fasting page. Related schedules include Alternate-Day Fasting, Prolonged Fasting and One Meal a Day, and eating one meal a day asks for far more fasting than the windows tested in most trials. Religious fasting, such as fasting from dawn to sunset during Ramadan, is a practice with its own meaning and rules, and section 3 describes how a coach meets it. And talk of fasting and ketones can lead a client to confuse an eating window with the Ketogenic Diet, which changes what a person eats rather than when.

2. In practice

A typical day of eating

A person following a late 8-hour window, noon to 8 p.m., might start the morning with water and black coffee or plain tea. Lunch at noon is a turkey or bean wrap with vegetables and a piece of fruit. An afternoon snack is yogurt and a handful of nuts. Dinner around 7 p.m. is chicken, fish or tofu with rice and roasted vegetables, and nothing with calories follows after 8. A person following an early window, 8 a.m. to 4 p.m., eats a full breakfast, a main meal at midday and an early dinner or substantial snack before 4, then nothing with calories in the evening.

Nothing about the food is special in either example; what defines the day is the clock. The same window could hold fast food and sweetened drinks, which is why food choices inside the window matter separately. These sample days are illustrations, not plans.

Cost, products, and who profits

The pattern itself is free. A client can follow it with the groceries they already buy, and fewer evening snacks may lower a food bill, although the searches for this page found no study that measured cost. No single company owns time-restricted eating, so there is no program price to report.

Where money enters, it is mainly through fasting apps; the searches for this page did not identify a study of what such apps cost users. The authors of a study of 2 free fasting apps reported 2.5 million downloads from 2018 to 2020, and most of the authors were employees of the company that made the apps and held ownership rights in it (Torres et al., 2022). Several trials used a research app, myCircadianClock, to record eating times (Oldenburg et al., 2025; Manoogian et al., 2024). A client does not need any app to keep an eating window.

For someone with limited money, the pattern adds no cost. For someone with little time, fewer meals or snacks to prepare can help. For someone who works nights or rotating shifts, the trial evidence is thin: several of the trials this page relies on excluded night-shift workers (Pavlou et al., 2023; Oldenburg et al., 2025), and section 3 describes the few trials that included them.

Environmental footprint

The searches for this page found no study estimating the environmental footprint of time-restricted eating itself. Because the pattern sets timing rather than food choices, the footprint depends mostly on which foods a person eats within the window.

Cultural fit

Timing is cultural. Many households build their days around shared meals, and a window that closes before the family dinner, or opens after the work lunch, can mean eating apart from other people. The authors of a Chicago trial chose noon to 8 p.m. and noted that American adults who practice time-restricted eating tend to place their window in the afternoon or evening so they can keep eating dinner with family and friends (S. Lin et al., 2023). Early windows fit less easily into evening meal traditions; late windows fit less easily where the main meal is at midday. A window can be shifted to fit a household, and self-selected windows were common in the trials (Parr et al., 2026; Oldenburg et al., 2025).

Fasting also has meaning in many faith traditions. A client who fasts for religious reasons, such as during Ramadan, is following a practice, not a diet, and the coach meets it with respect and curiosity rather than evaluation. The Intermittent Fasting page describes the health questions that can arise for people with diabetes who fast for religious reasons; those belong with their clinicians.

What makes people stop

The trial records point to the clock itself. In a 14-week trial of an early window, 24 percent of the early-window group and 20 percent of the comparison group dropped out, and 2 people in the early-window group withdrew because the schedule was hard to follow, against none in the comparison group (Jamshed et al., 2022). In a 12-month Australian trial of a self-chosen 9-hour window, more people left because of the intervention in the eating-window group than in the dietitian-advice group between months 4 and 12, 13 against 7 (Parr et al., 2026). In the 12-month Chicago trial, 13 percent of the eating-window group dropped out, all in the first 6 months, compared with 17 percent of the calorie-counting group (S. Lin et al., 2023).

People describe the reasons in their own words. After a 12-week trial, participants who had followed an eating window reported morning hunger that affected concentration and difficulty fitting the window around work, family and social events; one wrote of the difficulty of "scheduling meals at times different than family" (D. A. Chen et al., 2026). A review of 13 qualitative studies found barriers that were biological, such as hunger and cravings, psychological, such as emotional eating, and social, such as shared meals (Fernández-Rodríguez et al., 2026). Not every result points the same way: participants in a pregnancy trial kept an average window of 9.9 hours before pregnancy, though adherence fell during pregnancy (Sujan et al., 2025), and adherence in a 3-arm Spanish trial was 85 to 88 percent (Dote-Montero et al., 2025).

What happens when you stop

Few studies followed people after the window ended. In a 12-month follow-up of 99 participants from a 12-week Spanish trial of early, late and self-selected windows, the early-window and late-window groups had kept more of their weight loss than the usual-care group, and 26 percent reported practicing time-restricted eating at some point during that year (Camacho-Cardenosa et al., 2026). That follow-up was read for this page as its abstract, which does not say how its 99 participants relate to the 197 people randomized in the main trial, and it describes what happened after a 12-week program ended, not a year-long comparison of programs.

In a smaller follow-up of a 12-week Minnesota trial, the 23 eating-window participants who answered surveys reported keeping their weight steady for 6 months, and about half or fewer were still keeping a window at 1, 3 and 6 months, 52, 36 and 47 percent; weight in that follow-up was self-reported (D. A. Chen et al., 2026).

Within longer trials, differences that appeared early often narrowed. In the Australian 9-hour trial, the window was not worse than dietitian advice for long-term blood sugar at 4 months, but by 12 months the trial could no longer reach that conclusion, and the changes in both groups were small (Parr et al., 2026). A 2025 review found that in trials of at least 24 weeks, no fasting pattern, time-restricted eating included, differed from daily calorie restriction in weight change (Semnani-Azad et al., 2025).

Common variations

Within time-restricted eating, the window can be early, late or self-selected, and it can be 6, 8, 9, 10 or 12 hours long. Some programs pair the window with a calorie target (Liu et al., 2022; Jamshed et al., 2022), some with Mediterranean diet education (Dote-Montero et al., 2025), some with exercise (Hamsho et al., 2026), and some with dietitian counseling (Parr et al., 2026; Oldenburg et al., 2025). Programs for shift workers have used a 10-hour window placed around the working day (Manoogian et al., 2022), and a school trial in China used a 12-hour window with the last meal before 8 p.m. (Wu et al., 2026).

Other fasting schedules are separate patterns. The 5:2 pattern and alternate-day fasting are described and rated on the Intermittent Fasting page. Related schedules include Alternate-Day Fasting, Prolonged Fasting and One Meal a Day.

3. For the coach

SCOPE OF PRACTICE

A health and wellness coach does not prescribe, adjust, endorse or discourage time-restricted eating or any other way of eating, and does not diagnose or treat. The coach does not choose an eating window, a fasting length or a calorie target for a client. The coach helps the client understand what they have chosen, notice how it is going, and decide what to do next.

Five points belong to someone else. A client who takes insulin, a sulfonylurea or another medicine that lowers blood sugar, or who has type 1 diabetes, talks with the prescriber before moving or shortening meals, because doses and monitoring may need to change. A client who is pregnant, breastfeeding or trying to become pregnant plans any change in eating with the obstetric team. A client with a history of an eating disorder makes any plan with their clinician under their existing care plan. A young person's eating belongs to the family and the pediatric care team. And a client with chronic kidney disease involves the kidney care team, whose advice depends on the stage of the disease, lab results and whether the person is on dialysis.

Who does what

The physician

Decides whether an eating window is medically safe for this person and adjusts any medication it affects. For diabetes, that means deciding whether the doses or timing of insulin, sulfonylureas or other glucose-lowering medicines should change and how blood sugar will be monitored; the American Diabetes Association's 2026 standards state that "people with diabetes who are taking insulin and/or secretagogues should be medically monitored during the fasting period" (American Diabetes Association Professional Practice Committee for Diabetes, 2026). Orders and reads the tests that matter, such as HbA1c, and evaluates symptoms such as dizziness, fainting or weight loss the person did not intend.

The registered dietitian

Designs and monitors an individual plan that fits the window: enough protein, fiber and overall nutrition across fewer eating hours, and adaptations for diabetes, kidney disease, pregnancy, older age, shift work or heavy training. In several trials, dietitians delivered the eating-window programs and helped participants plan for hunger, social occasions and routines (Parr et al., 2026; Oldenburg et al., 2025). Screens for a history of dieting and disordered eating.

The health and wellness coach

Helps the client see their own reasons for choosing an eating window and test it against the life they lead: work hours, shifts, family meals, sleep, exercise, social plans and how hunger affects mood and concentration. Helps the client build a routine they own, notice what the experience is like from week to week, and keep their prescriber informed. With the client's permission, the coach can share general information from recognized authorities, such as what a diabetes guideline says about fasting with diabetes medicines, and explore how the client wants to use it. The coach notices whether the window is widening or narrowing the client's life and holds the referral line.

What a client bringing this diet needs

Clients arrive with an eating window for different reasons: a friend lost weight with 16:8, a podcast said that late eating harms the body clock, they are tired of counting calories, they already skip breakfast and want a name for it, or they read a headline that 16:8 raises the risk of heart disease and are worried. A client with diabetes may hope the window helps blood sugar; a client who works nights may want a structure that fits irregular days. The reason shapes the conversation.

What the coaching conversation offers that a search engine cannot is a careful look at fit. A window asks a person to be hungry at predictable times and to arrange eating around a clock, which can feel freeing to one person and confining to another. With permission, the coach can share what the research shows, that most trials found results similar to eating a little less every day, and then hand the decision back. The useful questions are about this person's days: when they are hungriest, who they eat with, what their sleep and work hours are, and what they will do if the plan is not working.

What to ask

• "What drew you to an eating window, and what are you hoping will be different?"
• "Walk me through a usual day and a hard day. Where would the window fit, and where would it pinch?"
• "Who else would this affect, like the people you eat with or the doctor who prescribes your medicines?"

Referral red flags

A client who takes insulin, a sulfonylurea or another blood sugar lowering medicine and is starting or has started an eating window without telling the prescriber needs to talk with the prescriber before going further. In a trial of an 8-hour window in adults with type 2 diabetes, doses of sulfonylureas and short-acting insulin were reduced or stopped under a written protocol set by each person's starting HbA1c (Pavlou et al., 2023). A client with type 1 diabetes is in the same position. A small trial in adults with type 1 diabetes used glucose monitoring and clinical insulin management; it does not establish the safety of starting an eating window without that care (Runchey et al., 2026).

If a client describes what sounds like a low blood sugar episode, such as feeling shaky, sweaty, dizzy or confused before the window opens, the first step is the client's own diabetes treatment plan; severe symptoms, or an episode the person cannot manage under that plan, call for emergency help. Telling the prescriber is the separate step that follows. The coach does not diagnose the cause.

A client who is pregnant, breastfeeding or trying to become pregnant, a teenager, or a client with chronic kidney disease is a referral before any eating-window plan. So is a client who reports fainting, persistent dizziness, new palpitations, or weight loss they did not intend; each is a reason to see a clinician, who works out the cause.

A client whose window comes with eating a great deal as soon as it opens, distress or guilt about eating outside it, a window that keeps shrinking, or withdrawal from meals with other people is worth asking about directly: what the window is for, whether it causes distress, whether it is narrowing what they eat, and whether it gets in the way of daily life. There are ordinary reasons to eat within set hours, such as work schedules, appetite and family routines. Where the answers raise a real concern about disordered eating, the coach follows their own referral process, or involves the client's clinician under an existing care plan.

Special populations

Pregnancy and breastfeeding

Several of the trials read for this page excluded people who were pregnant or trying to become pregnant (Lowe et al., 2020; Liu et al., 2022; Pavlou et al., 2023; Oldenburg et al., 2025). Two Norwegian trials tested a window of up to 10 hours in people at higher risk of gestational diabetes. In a 5-week feasibility trial of 32 pregnant participants, 30 completed; the window narrowed from about 12.3 to 9.9 hours, evening hunger rose, and glucose, blood pressure and body composition did not differ from usual care (Skarstad et al., 2024). A second trial randomized 167 people contemplating pregnancy to a window plus exercise training, started before pregnancy and continued through it, or to standard care; 111 became pregnant. The combined program did not clearly change the 2-hour glucose tolerance test at 28 weeks, and adherence fell during pregnancy (Sujan et al., 2025). That trial cannot isolate the effect of the window, and neither trial establishes safety across pregnancy or breastfeeding. Eating during pregnancy and breastfeeding is planned with the obstetric team.

Children and adolescents

The trials in young people are small, short or both. In adolescents with obesity, an 8-hour window over 12 weeks did not change energy intake or diet quality compared with a control group (Bakhsh et al., 2024). In 27 adolescents and young adults with newly diagnosed type 2 diabetes taking metformin, a late 8-hour window was feasible and no adverse events were reported, with no clear difference from the control group after 12 weeks (Hegedus et al., 2024). A 12-month school trial in China, read for this page as its abstract, randomized classes rather than children, used a 12-hour window, lost about 40 percent of its 192 participants to follow-up and was registered after it began (Wu et al., 2026). A young person's eating belongs to the family and the pediatric care team, and a coach works with the adult in front of them.

Older adults

In a 9-month pilot trial in 90 adults aged 60 and older, participants assigned to an 8-hour window reported keeping within 8.5 hours on a median of 84 percent of days, and their average weight change was about 1 kilogram, smaller than in the calorie restriction groups, which lost both fat and lean tissue (Houston et al., 2026). Losing muscle matters more with age, and some trials in younger adults found small losses of lean mass with an eating window (section 4). An older adult considering a window, especially one who is frail, has a small appetite or takes several medicines, needs the physician and a dietitian involved.

Athletes and people with high activity

Two 2026 reviews, read for this page as abstracts, pooled small trials. In 245 athletes, an eating window did not significantly change energy intake, lean mass, aerobic capacity, strength or power, with small reductions in body mass and body fat percentage, and certainty ranged from very low to moderate (R. Lin et al., 2026). In 8 trials of people doing resistance training, windows of 8 to 10 hours reduced fat mass slightly without a significant change in fat-free mass (Ali et al., 2026). Energy and protein needs at high activity are individual and belong with a sports dietitian.

People who work nights or rotating shifts

In a trial of 137 firefighters working 24-hour shifts, a 10-hour window was feasible, the average window narrowed from about 14.1 to 11.1 hours, no adverse effects were reported, and participants reported better quality of life (Manoogian et al., 2022). A 2025 review of 6 trials in shift workers found no significant effect on glucose measures and rated the certainty very low (Koh et al., 2025). Shift work changes the body clock as well as meal times, and a plan for a shift worker belongs with a clinician or dietitian who knows the person's schedule.

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

Diabetes medicines matter most. Insulin and sulfonylureas carry the highest risk of low blood sugar when meals move or shrink, and in the trials, dose changes were made under medical supervision with a written protocol (Pavlou et al., 2023). The American Diabetes Association's standards call for medical monitoring of people taking insulin or secretagogues during fasting (American Diabetes Association Professional Practice Committee for Diabetes, 2026). The searches for this page did not identify a trial of time-restricted eating that tested its effects in people taking warfarin or in people whose main concern was blood pressure medication. For a client taking insulin, a sulfonylurea, blood pressure medicine or warfarin, a substantial change in eating is something the client discusses with the prescriber before making it.

People with a history of disordered eating

Trials usually screen out people with a history of eating disorders (Pavlou et al., 2023; Oldenburg et al., 2025), so the trials say little about them. In community samples, intermittent fasting, including daily fasting of about 16 hours, has been associated with more eating disorder symptoms, and the Intermittent Fasting page reviews those studies and rates that association. These studies cannot show whether fasting causes symptoms or whether people with symptoms are drawn to fasting. For a client with this history, any plan is made with their clinician; the Intuitive Eating and Mindful Eating pages describe approaches built around internal cues rather than a clock.

People with kidney disease

In a 12-month pilot trial in adults with polycystic kidney disease, an eating window and healthy eating advice without a window led to similar modest weight loss, and adherence to the window varied (Steele et al., 2025). Kidney needs depend on the stage of the disease, lab results and dialysis, and the kidney care team decides.

Client misconceptions

Three come up often. The first is that the window burns fat in a way ordinary dieting does not. In trials comparing an eating window with daily calorie restriction, weight change was about the same (Semnani-Azad et al., 2025), and in the trials read for this page, people who lost weight with a window also ate less. The second is that anything goes inside the window. In a 12-week trial comparing noon-to-8-p.m. eating instructions with instructions for structured mealtimes, weight loss was not significantly different between the groups (Lowe et al., 2020).

The third is that 16:8 has been shown to double the risk of dying from heart disease. That idea comes from a 2024 conference abstract and its press coverage, later published as an observational study of people's usual eating hours on 2 recalled days, not of people following an eating-window plan, and its authors wrote that other factors linked to a short eating day may explain the finding (M. Chen et al., 2025). Section 6 gives each myth with its origin.

🤝 COACHING CONNECTION

Luis, 41, a nurse who works three 12-hour night shifts a week, tells his coach he wants to try 16:8 after seeing a video saying that eating at night "wrecks your body clock." He takes no medicines. The coach asks what he hopes will change. Luis says he wants more energy on his days off and fewer vending-machine snacks at 3 a.m.

The coach asks whether he would like to hear what the research says. He says yes, and the coach shares that most eating-window trials excluded night-shift workers, and that a trial in firefighters working 24-hour shifts used a 10-hour window chosen around each person's work. Luis says the 8-hour window in the video would mean not eating for his whole shift. He decides to start by packing his own meal for the shift and to raise the question of meal timing with his primary care provider at his next visit. The coach did not recommend a window, set hours or comment on his health.

4. The evidence

(select the heading to open or close this section)

The trials of time-restricted eating are numerous, mostly short and mostly small, and they answer three different questions that this page keeps apart. Against making no change to when people eat, an eating window led to a small loss of weight that the largest review called trivial. Against eating a little less every day, it produced about the same weight change. Between early and late windows, one review found a small advantage for early windows and others did not. No trial identified for this page measured heart attacks, strokes or deaths.

Every row of the rating table at the foot of this page names one of these comparisons. Results against no change in timing and results against daily calorie restriction are never pooled, because they ask different things: the first asks whether a window helps compared with carrying on as usual, and the second asks whether it helps more than an ordinary diet. The 5:2 pattern, alternate-day fasting and prolonged fasting are not reported here; the Intermittent Fasting page reports and rates them.

Evidence from randomized controlled trials

A trial assigns people to the diet by chance and compares them with people assigned to something else, which is the strongest way to test whether the diet itself causes a result. Four reviews limited to time-restricted eating, or reporting it as its own category, carry most of the weight here. A 2025 network meta-analysis of 99 trials of intermittent fasting included 40 trials with an eating-window arm; it rated its findings with CINeMA, a GRADE-based method for comparing several approaches at once, and judged a 2-kilogram difference in weight to be the smallest that matters (Semnani-Azad et al., 2025).

A 2026 network meta-analysis of 41 trials with 2,287 participants, searched to January 2023, sorted eating windows by timing and length; its median trial lasted 8 weeks, and it also used CINeMA (Y.-E. Chen et al., 2026). A second 2026 network meta-analysis of 39 trials with 3,236 participants, searched to April 2025, used GRADE (Hamsho et al., 2026). A 2026 review of 10 trials with 599 participants with prediabetes or type 2 diabetes used GRADE as well (Viple et al., 2026). A network meta-analysis combines direct comparisons from trials that tested 2 approaches head to head with indirect comparisons through a shared comparison group.

Cardiometabolic outcomes

For long-term blood sugar, measured as HbA1c, the 2025 review did not detect a difference between an eating window and daily calorie restriction, or between an eating window and usual eating, and it rated each of those 2 comparisons moderate in certainty (Semnani-Azad et al., 2025). In 75 adults with type 2 diabetes in Chicago, HbA1c fell by about 0.9 percentage points more than in a control group with both an 8-hour window and daily calorie restriction, with no significant difference between the 2 (Pavlou et al., 2023). In 247 Australian adults at risk of type 2 diabetes, a self-chosen 9-hour window was not worse than individual dietitian advice for HbA1c after 4 months, but by 12 months the trial could no longer conclude that it was not worse; the changes in both groups were small (Parr et al., 2026).

In people with prediabetes or type 2 diabetes, the 2026 review limited to them reported that an eating window did not clearly lower HbA1c compared with a control diet without a window, a difference of 0.30 percentage points with an interval from 0.63 lower to 0.02 higher, which it rated moderate in certainty using GRADE; that interval does not establish that the window and the control diet are equivalent, or that the window brings a clinically important improvement. Fasting glucose fell slightly, also rated moderate (Viple et al., 2026). These ratings are reported here as published and are not added to the rating table, whose HbA1c rows come from a different population and mix of comparisons.

In a 3-month trial in 122 adults with metabolic syndrome, 108 of whom completed it, adding a personalized 8- to 10-hour window to standard care lowered HbA1c by 0.10 percentage points more than standard care alone, with an interval from 0.19 to 0.003 lower (Manoogian et al., 2024).

For blood pressure, the 2026 timing review found that eating windows lowered systolic pressure by about 4.9 mm Hg compared with usual diets, with no effect on diastolic pressure (Y.-E. Chen et al., 2026); in the other 2026 network review, only early windows lowered systolic pressure significantly compared with control, by about 2.6 mm Hg (Hamsho et al., 2026). For blood fats, the timing review found that windows shorter than 8 hours raised total and LDL cholesterol compared with usual diets, LDL by about 4.5 mg/dL, which it rated high in certainty, while longer windows did not (Y.-E. Chen et al., 2026). The authors suggest that the longer fast before a morning blood test may explain part of this.

The idea that the clock matters apart from eating less rests largely on small, closely controlled studies. In a crossover study, 8 men with prediabetes who ate within a 6-hour window ending by mid-afternoon, with enough food to keep their weight steady, had lower morning blood pressure by about 11 and 10 mm Hg and better insulin sensitivity after 5 weeks than on a 12-hour schedule, while their morning triglycerides rose; the tests after the early-window period followed a longer overnight fast, and the authors noted that some effects appeared to carry over between periods (Sutton et al., 2018).

In a 2025 crossover trial of 31 women with overweight or obesity who were asked to eat their usual food in either an early or a late 8-hour window for 2 weeks each, neither window improved insulin sensitivity or other cardiometabolic measures (Peters et al., 2025). The design intended calories to stay the same, but participants ate slightly less and lost a little weight on the early window, so calories were not held exactly equal; that trial was read for this page as its abstract.

No trial identified for this page measured heart attacks or strokes as outcomes of an eating window.

Cancer

The searches for this page identified no trial of time-restricted eating that measured whether people developed cancer. Small studies in people already living with cancer measured feasibility, symptoms and markers, and the Intermittent Fasting page describes a review of them. What the studies reviewed do not establish is whether an eating window prevents cancer or changes its course.

Body weight, as measured

This archive reports body weight as something a study measured, in that study's own numbers, and not as a goal or as a measure of whether an eating pattern worked; see the standing rule in the review record at the foot of this page. The one exception is weight a person loses without meaning to, which can signal a health problem and is a reason to involve a clinician, never a sign that a diet worked.

Against no change in eating times. In the 2025 review, eating windows reduced weight by 1.72 kilograms compared with usual eating, with an interval from 1.22 to 2.21 kilograms, across 25 trials that compared the 2 directly; the review rated this moderate in certainty and classed it as trivial, because it fell below its 2-kilogram threshold (Semnani-Azad et al., 2025). The 2026 timing review reported a reduction of 2.15 kilograms, with an interval from 1.74 to 2.56, in trials with a median length of 8 weeks (Y.-E. Chen et al., 2026).

Individual trials varied. In a 12-week app-based trial that randomized 141 adults and analyzed 116, the difference between instructions to eat from noon to 8 p.m. and instructions for 3 structured meals a day was 0.26 kilograms and not significant (Lowe et al., 2020). A 2021 correction clarified the messages participants received, including initial advice about easing into fasting; the comparison was between instruction packages, not a controlled test holding everything except timing constant.

In a 12-week Minnesota trial of 88 adults, a self-selected 8-hour window led to 1.4 kilograms more weight loss than unrestricted eating, with an interval from 4.5 kilograms more to 1.7 kilograms less, a difference that was not significant; the window people kept averaged 9.8 hours (Oldenburg et al., 2025). In a 12-week trial of 61 adults with obesity who usually ate across 14 hours or more, a 10-hour window led to 2.91 kilograms more weight loss than standard dietary counseling, with an interval from 1.60 to 4.21 (Wilkinson et al., 2026). In the 12-month Chicago trial of 90 adults, the window reduced weight by 4.61 kilograms more than the control group (S. Lin et al., 2023).

Against daily calorie restriction. In the 2025 review, the difference between an eating window and daily calorie restriction was 0.39 kilograms favoring calorie restriction, with an interval from 1.02 favoring calorie restriction to 0.23 favoring the window, across 14 direct trials; the review rated this moderate in certainty, and in trials of at least 24 weeks it did not detect a difference (Semnani-Azad et al., 2025).

In 139 adults with obesity in China, all given the same calorie targets, adding an 8 a.m. to 4 p.m. window produced no clear difference in weight loss over 12 months: a net difference of 1.8 kilograms more loss with the window, with an interval from 4.0 kilograms more to 0.4 kilograms less; 118 of the 139 completed the 12-month visit (Liu et al., 2022). Both groups received calorie targets, frequent research-staff support and a daily protein shake for the first 6 months; this tests adding an early window to a supported program, not an unsupervised window alone. The trial reported no deaths or serious adverse events, which does not show that a window is safe in general.

In the Chicago trial, the window group lost 0.81 kilograms less than the calorie-counting group at 12 months, with an interval from 3.07 kilograms more to 4.69 kilograms less, a difference that was not significant; 77 of 90 completed (S. Lin et al., 2023). One trial found a difference. In 90 adults with obesity who all received the same weight-loss counseling, an early 8-hour window from 7 a.m. to 3 p.m. led to 2.3 kilograms more weight loss than a window of 12 hours or more over 14 weeks, with an interval from 0.9 to 3.7; 59 participants had final measurements, partly because the COVID-19 pandemic interrupted testing (Jamshed et al., 2022). A 2024 review of 7 trials that matched calories between groups found that most did not detect an added benefit from the window (Ezzati et al., 2024).

Lean mass. Lean mass is the weight of everything except fat, including muscle. In the app-based trial, among the 50 people measured in person, the window group lost more lean mass in the arms and legs than the 3-meals group, 0.47 kilograms more (Lowe et al., 2020). In the 2026 timing review, eating windows reduced fat-free mass by 0.84 kilograms compared with usual diets (Y.-E. Chen et al., 2026), and a 2025 review found reductions of 0.58 kilograms against no restriction and 0.56 kilograms when windows were added to calorie restriction (Sun et al., 2025). In the metabolic syndrome trial, the window group did not lose more lean mass than the standard care group (Manoogian et al., 2024). In the 2026 timing review, fat mass fell more than fat-free mass (Y.-E. Chen et al., 2026).

Mortality

No trial identified for this page measured deaths as an outcome of an eating window. The trials were mostly too short and too small to do so. The observational studies of usual eating hours and death are described under the cohort evidence below.

Eating behavior and wellbeing

In trials, which usually screen people carefully, eating windows have not clearly worsened measured eating behavior, but they do change hunger. A 2023 review of 16 studies found that disordered eating questionnaires did not change with an eating window, that hunger at bedtime was higher, and that interviews described fear of hunger, eating when not hungry and eating-related stress (Vizthum et al., 2023). A 2025 review of 4 trials with 323 participants found more hunger with an eating window than with comparison diets of the same calories (Silva et al., 2025). Both were read for this page as abstracts. These results come from people who were screened and supported; the community studies described on the Intermittent Fasting page point in a less reassuring direction.

For sleep, mood and quality of life, the 3-arm Spanish trial found no significant differences between any of its windows and usual care after 12 weeks (Clavero-Jimeno et al., 2025), and a 2026 review found no differences in sleep in its controlled trials (Jin et al., 2026). In the 14-week early-window trial, the window group improved more on several mood scales, including fatigue and vigor (Jamshed et al., 2022). For diet quality, a 2026 review of 5 small studies found inconsistent effects, with more favorable results when the window came with nutrition guidance (Flynn et al., 2026). Side effects in the trials were mostly mild. The 2026 timing review reported no serious adverse events in the 14 trials with data, with dizziness, headache and constipation in some participants (Y.-E. Chen et al., 2026).

Evidence from long-term prospective cohort studies

A cohort study follows people who already eat a certain way and records what happens to them. It can show that a pattern goes with an outcome; it cannot by itself show that the pattern caused it. The cohort studies of eating windows estimate a person's usual eating hours from a few days of recalled eating, and a short usual window may come from illness, poverty, work schedules or a deliberate plan; the studies cannot tell these apart.

Cardiometabolic outcomes

A 2026 review of observational studies of eating windows of 12 hours or less found 12 cross-sectional and 6 cohort studies. In the cross-sectional studies, a short eating window was not associated with abdominal obesity, metabolic syndrome, high blood pressure, low HDL cholesterol, high triglycerides, or prediabetes and type 2 diabetes, and the review found too few prospective data to draw conclusions (Feit et al., 2026).

Cancer

The searches for this page did not identify a cohort study following people who intentionally adopted an eating window for new cases of cancer. Studies of usual overnight fasting in people who already had cancer ask a different question; the Intermittent Fasting page describes one.

Body weight, as measured

The searches for this page did not identify a cohort study following measured weight in people who intentionally adopted an eating window. The cross-sectional studies in the 2026 review did not find a consistent association between a short eating window and abdominal obesity (Feit et al., 2026).

Mortality

In 19,831 United States adults followed for a median of 8.1 years, a usual eating window shorter than 8 hours, measured from 2 days of recalled eating, was associated with a higher rate of death from cardiovascular disease than a window of 12 to 14 hours, a hazard ratio of 2.35, from 1.39 to 3.98. It was not associated with death from any cause or from cancer, and only 383 people were in the shortest-window group (M. Chen et al., 2025). The authors wrote that the association may reflect the short window itself or other factors linked to it.

A second analysis of the same national survey, in 33,052 adults, found the lowest death rates with windows of about 11 to 12 hours and higher rates with both shorter and longer windows (Mao et al., 2025). These studies describe habits on 1 or 2 days, not an eating-window plan, and section 6 traces how the first one became a headline.

Highlighted studies

These 4 carry the most weight for this page: the review that compared early, middle and late windows, 2 year-long trials against calorie restriction, and the largest trial comparing early, late and self-selected windows with usual care. The 2025 network meta-analysis of all fasting patterns is highlighted on the Intermittent Fasting page.

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

Highlighted studies for Time-Restricted Eating

Study	Design	Sample size	Duration	Finding	The limitation that matters
Y.-E. Chen et al., 2026	Systematic review and network meta-analysis of randomized trials, certainty rated with CINeMA	41 trials, 2,287 participants	Trials of 4 to 48 weeks, median 8	Compared with usual diets, eating windows reduced weight by 2.15 kilograms. Early windows, with the last meal before 5 p.m., reduced weight by 1.15 kilograms more than late windows, after 7 p.m. (published as high certainty)	Mostly short trials; only 2 trials compared early and late windows directly, and their combined result alone did not clearly differ; the authors wrote that their certainty ratings may be optimistic
Liu et al., 2022	Randomized controlled trial: 8 a.m. to 4 p.m. window plus calorie restriction, or calorie restriction alone	139 adults with obesity in China	12 months	Weight fell 8.0 kilograms with the window and 6.3 with calorie restriction alone; the difference was not significant	Both groups received calorie targets, frequent research-staff support and a daily protein shake for the first 6 months; this tests adding an early window to a supported program, not an unsupervised window alone
S. Lin et al., 2023	Randomized controlled trial: noon to 8 p.m. window without calorie counting, daily calorie restriction, or control	90 adults with obesity, mostly Black and Hispanic	12 months, with the window widened to 10 hours after 6 months	Compared with control, weight fell 4.61 kilograms with the window and 5.42 with calorie restriction; no significant difference between them	Small and unblinded, and not designed to detect small differences between the 2 active approaches
Dote-Montero et al., 2025	Randomized controlled trial: early, late or self-selected 8-hour window plus Mediterranean diet education, or education alone	197 adults with overweight or obesity in Spain	12 weeks	No significant difference in visceral fat between any window and usual care, or among the windows; weight fell more than with usual care in all 3 window groups, with no difference detected among them	Short; all groups had dietitian-led meetings every 2 weeks; read for this page as the authors' accepted manuscript, not the published version

Head to head

Early against late windows. Researchers do not define early and late the same way. The 2026 timing review sorted windows by the last meal, early meaning before 5 p.m. and late after 7 p.m. (Y.-E. Chen et al., 2026). The other 2026 network review sorted them by the first meal, early meaning before 10 a.m. and late after noon (Hamsho et al., 2026). The Spanish trial started early windows before 10 a.m. and late windows after 1 p.m. (Clavero-Jimeno et al., 2025). A client's "early" may be any of these.

The 2026 timing review estimated that early windows reduced weight by 1.15 kilograms more than late windows, with an interval from 0.45 to 1.86, and fasting insulin by more, and rated the weight comparison high in certainty (Y.-E. Chen et al., 2026). Its supplement shows that only 2 trials compared early and late windows directly, and their combined direct estimate, 0.89 kilograms, had an interval that crossed no difference; the network estimate also drew on indirect comparisons. The review set no threshold for an important difference; the estimate is below the 2-kilogram threshold used in the 2025 fasting review (Semnani-Azad et al., 2025), and the authors wrote that their certainty ratings may be optimistic.

Other reviews have not consistently detected a timing advantage. The second 2026 network review found no significant differences between early, midday and late windows and calorie restriction for most outcomes, with certainty from very low to moderate, though early windows ranked near the top for several blood sugar measures and were the only windows to lower HbA1c significantly against control (Hamsho et al., 2026). The Spanish trial did not detect a significant difference among its early, late and self-selected windows in visceral fat (Dote-Montero et al., 2025).

In the crossover trial in women, the midpoint of sleep was about 15 minutes later on the late window than on the early one, and body-clock timing measured in blood cells was also later, though that difference was not statistically clear; neither window changed insulin sensitivity (Peters et al., 2025). Whether an early window adds anything over a late one, outside short trials, is not settled, and a difference in weight change does not show that timing itself brings lasting benefit apart from calories or weight change.

Against other fasting patterns and named food patterns. The 2025 review compared eating windows with alternate-day fasting and whole-day fasting; the Intermittent Fasting page reports those comparisons. Some trials combine a window with a named food pattern instead of comparing them: in the Spanish trial, adding any of the 3 windows to Mediterranean diet education did not reduce visceral fat more than the education alone over 12 weeks (Dote-Montero et al., 2025). The Mediterranean Diet page carries the evidence on that pattern.

Where the evidence is absent

• The trials identified for this page did not measure heart attacks, strokes, cancer or deaths. Whether an eating window changes those outcomes is not established by the studies reviewed.
• Few trials lasted a year or more, and the searches found only a few studies that followed people after a program ended, read for this page as an abstract or with self-reported weight (Camacho-Cardenosa et al., 2026; D. A. Chen et al., 2026).
• Most trials were in adults with overweight or obesity. Evidence in children and adolescents, pregnancy, older adults with frailty, athletes, shift workers, type 1 diabetes and kidney disease is limited to a few trials, most of them small or short, and the searches did not identify a trial in people with an eating disorder history.
• The searches did not identify a trial testing an eating window in people taking warfarin, a study measuring cost, or an estimate of the environmental footprint.
• The cohort studies of eating hours describe usual habits recorded on a few days of recalled eating, not intentional eating windows, and cannot separate a plan from illness, work schedules or poverty.
• Definitions of the window, of early and late, and of what breaks a fast differ from study to study, which makes trials hard to compare; a 2023 federal workshop named standard terms and measures as a first need for the field (Dashti et al., 2025).

5. Mechanisms

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

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

Established mechanisms

Eating less. Reduced energy intake explains much of the weight change observed in these trials. In the 12-month Chicago trial, people with a noon to 8 p.m. window reported eating about 425 fewer calories a day, about the same as people counting calories (S. Lin et al., 2023), and adults with type 2 diabetes on the same window reported eating about 313 fewer (Pavlou et al., 2023). In the Minnesota trial, the more a person's window shrank, the more their calorie intake fell (Oldenburg et al., 2025). The 2023 federal workshop report concludes that the weight effects of time-restricted eating in people are at least partly explained by eating less, and that whether a shorter window changes energy balance in any other way "remains to be determined" (Dashti et al., 2025).

The body clock. The body keeps time with a master clock in the brain, in a region called the suprachiasmatic nucleus, and with secondary clocks in nearly every organ and tissue. Light is the main signal that sets the master clock. The timing of eating is a strong signal for the clocks in organs and tissues, and when eating and light send conflicting signals, the organ clocks can drift out of step with the master clock (Dashti et al., 2025). The American Diabetes Association's standards note that glucose tolerance varies across the day and is highest during daylight hours (American Diabetes Association Professional Practice Committee for Diabetes, 2026). These facts about the clock are well established. Whether an eating window improves health because of them is the proposed part, described next.

In people, changing meal times can move some of these rhythms. In the crossover trial in women, sleep came about 15 minutes later on a late window than on an early one, and the timing of the clock measured in blood cells moved in the same direction, though that difference was not statistically clear (Peters et al., 2025).

Proposed mechanisms

Eating in step with the clock. The circadian rationale for time-restricted eating, as the research states it, is that eating when the body handles food best, and fasting through the biological night, improves blood sugar control and metabolism beyond whatever weight is lost (Dashti et al., 2025; Y.-E. Chen et al., 2026). The evidence for this in people is mixed. A small study in 8 men found better insulin sensitivity and lower blood pressure with an early 6-hour window without weight loss, while morning triglycerides rose (Sutton et al., 2018). A trial of 31 women eating their usual food in early or late 8-hour windows found no improvement in insulin sensitivity with either (Peters et al., 2025). The American Diabetes Association's standards describe the study of meal timing, called chrononutrition, as an evolving area that "currently lacks conclusive evidence" (American Diabetes Association Professional Practice Committee for Diabetes, 2026).

Lessons from mice. In mice fed a high-fat diet, an 8-hour feeding window prevented obesity and fatty liver without reducing calories and improved the daily rhythms of clock genes and metabolic pathways in the liver (Hatori et al., 2012). Claims that eating windows repair cells, switch on fat burning or slow aging rest on animal work and on the proposed metabolic switch described on the Intermittent Fasting page. A mechanism shown in animals, or in a handful of people over a few weeks, is a reason to study a pattern, not evidence that it prevents disease.

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 found no regulatory warning about time-restricted eating itself. The warning that exists concerns diabetes medicines. The American Diabetes Association's 2026 standards state: "People with diabetes who are taking insulin and/or secretagogues should be medically monitored during the fasting period" (American Diabetes Association Professional Practice Committee for Diabetes, 2026). Secretagogues are medicines, such as sulfonylureas, that make the pancreas release more insulin. The same standards also call time-restricted eating safe for adults with type 1 or type 2 diabetes, citing a single journal-club commentary on one trial rather than a trial or a review; this page does not rely on that statement.

Nutrient gaps

The pattern removes no food, so it creates no built-in gap. In adolescents with obesity, an 8-hour window over 12 weeks did not change diet quality (Bakhsh et al., 2024), and a 2026 review of 5 small studies found inconsistent effects on diet quality in adults (Flynn et al., 2026). The open questions are about fitting enough into fewer hours. The authors of the app-based trial linked the lean mass loss they observed to the possibility that protein intake changed, which they did not measure (Lowe et al., 2020). Protein, fiber and overall food quality across a shorter eating day, especially for older adults, people with high activity, pregnant people and people with diabetes, are questions for a registered dietitian.

Who should not follow it without medical supervision

• People taking insulin, a sulfonylurea or another medicine that lowers blood sugar, because moving or shortening meals while taking them can bring blood sugar too low, and doses and monitoring may need to change (American Diabetes Association Professional Practice Committee for Diabetes, 2026; Pavlou et al., 2023).
• People with type 1 diabetes, for the same reason; the one small trial identified monitored glucose continuously and had a study endocrinologist adjust insulin, so it does not establish the safety of a window without that care (Runchey et al., 2026).
• People who are pregnant, breastfeeding or trying to become pregnant. Pregnancy evidence now includes a small feasibility trial and a combined lifestyle trial, as described under Special populations in section 3; it does not establish safety for self-directed fasting, and eating changes belong with the obstetric team (Skarstad et al., 2024; Sujan et al., 2025).
• People with a history of an eating disorder, who are screened out of most trials (Pavlou et al., 2023; Oldenburg et al., 2025) and for whom a rule about when eating is allowed can become part of the problem; the Intermittent Fasting page reviews the community studies.
• Children and adolescents, in whom the trials are small or short (Bakhsh et al., 2024; Hegedus et al., 2024; Wu et al., 2026).
• Older adults who are frail or losing muscle, because some trials found small losses of lean mass with an eating window (Lowe et al., 2020; Sun et al., 2025).
• People with chronic kidney disease, whose needs depend on the stage of the disease, lab results and dialysis; the one pilot trial identified was small (Steele et al., 2025). The kidney care team decides.
• People who work nights or rotating shifts and have a health condition, because the body clock and the meal clock both shift and the trial evidence is limited (Koh et al., 2025).

Medication interactions

A coach never adjusts medication. The point of knowing these is to know when to send the client back to the prescriber. Insulin and sulfonylureas carry the highest risk of low blood sugar when eating moves or shrinks. In the trial of an 8-hour window in type 2 diabetes, sulfonylureas were stopped or halved and short-acting insulin reduced according to each person's starting HbA1c, under a written protocol, and blood sugar was tracked with continuous glucose monitors at set points and with daily finger-stick tests in between (Pavlou et al., 2023). The Intermittent Fasting page describes how the American Diabetes Association's standards treat other diabetes medicines during fasting.

Some medicines are taken with food or at set times, and a window can make that harder; that is a question for the prescriber or pharmacist, never a reason for the client to move or skip a dose. The searches for this page did not identify a trial of time-restricted eating that tested its effects in people taking warfarin or in people whose main concern was blood pressure medication. Under the archive's standing rule, a client taking insulin, a sulfonylurea, blood pressure medicine or warfarin who plans a substantial change in eating keeps the prescriber informed before making it, rather than asking permission for every meal.

Signs it is going wrong

Physical signs a coach or a family member might notice include shakiness, sweating, dizziness, confusion or a racing heart before the window opens in someone taking diabetes medicine, which can mean low blood sugar; fainting; persistent headaches, tiredness or trouble concentrating; and weight loss the person did not intend. Each is a reason to involve a clinician, not a diagnosis. A possible low blood sugar episode is treated first under the person's own diabetes plan, with emergency help if symptoms are severe or the person cannot manage the episode under that plan; telling the prescriber follows.

Behavior matters as much and has to be read with care. Eating within set hours can come from work schedules, appetite, religious practice, a clinician's plan or family routines, so on its own it tells a coach little. Eating a great deal as soon as the window opens, guilt or anxiety after eating outside it, preoccupation with the clock or with food, a window that keeps shrinking, or turning down meals with other people carries more meaning and is worth asking about directly. The questions are the same in every case: 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 the client's existing clinical plan.

Myths and where they came from

Myth: "16:8 nearly doubles your risk of dying from heart disease."

Where it came from: a 2024 conference abstract and its press release, headlined "8-hour time-restricted eating linked to a 91% higher risk of cardiovascular death"; the release itself noted that abstracts are preliminary until published and that the association did not show that time-restricted eating caused the deaths (American Heart Association, 2024). The full analysis, published in 2025, reported a hazard ratio of 2.35 for a usual eating window shorter than 8 hours, from 2 days of recalled eating, in 383 people (M. Chen et al., 2025). What is true: the study measured habits, not an eating-window plan, and its authors wrote that other factors linked to a short eating day may explain the finding. The trials identified for this page did not measure deaths. The Intermittent Fasting page rates the association very low in certainty, and this page carries that rating.

Myth: "Eating late is what makes people gain weight, so the window burns fat by itself."

Where it came from: mouse experiments in which a feeding window prevented weight gain without fewer calories (Hatori et al., 2012). What is true: in trials comparing an eating window with daily calorie restriction, weight change was about the same (Semnani-Azad et al., 2025), and when women ate their usual food in an early or a late window for 2 weeks each, neither window improved insulin sensitivity (Peters et al., 2025). Section 4 gives the results.

Myth: "On 16:8 you can eat whatever you want, as long as it is in the window."

Where it came from: plans and trials that set no calorie limit inside the window. What is true: in those trials, people who lost weight reported eating fewer calories (S. Lin et al., 2023), and in a trial comparing noon-to-8-p.m. eating instructions with instructions for structured mealtimes, weight loss was not significantly different between the groups (Lowe et al., 2020). The principles of healthy eating still apply during the hours when people eat (American Diabetes Association Professional Practice Committee for Diabetes, 2026).

Myth: "Black coffee and diet soda never break the fast," or "anything but water breaks it."

Where it came from: differing plan rules. What is true: the trials do not agree. One allowed water and black coffee or tea, with an initial exception for people easing into the fast (Lowe et al., 2020), another allowed coffee, tea and up to 2 diet sodas a day (S. Lin et al., 2023), and a third counted every drink except water when it measured the window (Oldenburg et al., 2025). No rule is shown to be the right one, and medicines are taken as prescribed whatever the window.

Myth: "The shorter the window, the better."

Where it came from: the idea that more fasting must mean more benefit. What is true: the 2026 timing review found that the link between window length and outcomes was inconsistent, and windows shorter than 8 hours raised LDL and total cholesterol compared with usual diets (Y.-E. Chen et al., 2026). In the trials that measured it, an eating window also brought more hunger than a comparison diet with the same calories (Silva et al., 2025).

7. Key terms

Time-restricted eating

Eating all food and drink with calories within the same window of hours each day and having nothing with calories outside it.

Eating window

The hours of the day in which a person eats; studies define and measure it in different ways.

16:8

The common name for 16 hours without food and an 8-hour eating window; names such as 18:6 follow the same pattern.

Early time-restricted eating

A version in which the window falls early in the day; reviews define early by when the last meal ends or by when the first meal starts.

Late time-restricted eating

A version in which the window starts around midday or later and ends in the evening.

Self-selected window

An eating window of a set length whose start and end times the person chooses.

Daily calorie restriction

Eating a little less every day, also called continuous energy restriction; one of the 2 main comparisons in the trials.

Usual eating

The comparison in which people make no change to when they eat; reviews also call it an ad libitum or usual diet.

Isocaloric

Matched in calories by design, so that 2 groups are meant to eat the same amount and differ in timing; trials do not always achieve an exact match.

Circadian rhythm

An internal cycle of about 24 hours that times sleep, hormones and metabolism.

Central clock

The master clock in the brain, in the suprachiasmatic nucleus, set mainly by light.

Peripheral clocks

The clocks in organs and tissues such as the liver and muscle, for which the timing of eating is a strong signal.

Chrononutrition

The study of how the timing of eating affects the body clock and health.

Network meta-analysis

A method that combines direct comparisons from trials with indirect comparisons through a shared comparison group, so that several approaches can be compared at once.

CINeMA

A GRADE-based method for rating the certainty of results from a network meta-analysis.

HbA1c

A blood test that reflects average blood sugar over about the previous 3 months, used to monitor diabetes.

Lean mass

Everything in the body except fat, including muscle, organs, bone and water; reviews also call it fat-free mass.

Sulfonylurea

A diabetes medicine, such as glipizide, that makes the pancreas release more insulin and can cause low blood sugar if a person eats less or later than usual.

8. Review questions

1. Describe 3 things that define a particular version of time-restricted eating, and explain why a client who says "I do intermittent fasting" may need to be asked what they mean.
2. Using section 4, explain the 2 comparisons this page keeps apart for body weight, what the 2025 review found for each, and why the choice of comparison matters when a client says an eating window works.
3. A client who takes insulin for type 2 diabetes tells you she will start a noon to 8 p.m. window next month and has not told her doctor. What does the coach explore, what can the coach share with permission, and where exactly is the referral line?
4. Using sections 4 and 6, explain where the claim that 16:8 raises the risk of dying from heart disease came from, how the press coverage and the published study differ, and what the study cannot show. Write the 2 sentences you would use with a client who raises it.

9. References

Ali, A. M., Messenburger, G. P., Neves Collares, L. D., Nuñez, F. F., & Pieniz, S. (2026). Time-restricted eating shows a modest reduction in fat mass in resistance-trained individuals: A systematic review and meta-analysis. Nutrition Research, 147, 1-15. https://doi.org/10.1016/j.nutres.2026.01.001

American Diabetes Association Professional Practice Committee for Diabetes. (2026). 5. Facilitating positive health behaviors and well-being to improve health outcomes: Standards of care in diabetes-2026. Diabetes Care, 49(Suppl. 1), S89-S131. https://doi.org/10.2337/dc26-S005

American Heart Association. (2024, March 18). 8-hour time-restricted eating linked to a 91% higher risk of cardiovascular death [Press release]. newsroom.heart.org/news/8-hour-time-restricted-eating-linked-to-a-91-higher-risk-of-cardiovascular-death

Bakhsh, J. A., Vu, M. H., Salvy, S. J., Goran, M. I., & Vidmar, A. P. (2024). Effects of 8-h time-restricted eating on energy intake, dietary composition and quality in adolescents with obesity. Pediatric Obesity, 19(11), Article e13165. https://doi.org/10.1111/ijpo.13165

Camacho-Cardenosa, A., Merchán-Ramírez, E., Clavero-Jimeno, A., De-la-O, A., Romero-Noguera, J. M., Martín-Rodríguez, J. L., Muñoz-Torres, M., Labayen, I., Ruiz, J. R., & Dote-Montero, M. (2026). Effects of an early, late, and self-selected time-restricted eating intervention on weight loss maintenance in adults with overweight or obesity: A 12-month follow-up of a randomized controlled trial. Clinical Nutrition, 63, Article 106706. https://doi.org/10.1016/j.clnu.2026.106706

Chen, D. A., Pena, R. H., Oldenburg, N., Wang, Q., Helgeson, E., Yentzer, B., Taddese, A., LaPage, N., Manoogian, E. N. C., Panda, S., & Chow, L. S. (2026). Post-intervention sustainability of time-restricted eating versus caloric restriction: A secondary analysis. International Journal of Obesity, 50(2), 474-477. https://doi.org/10.1038/s41366-025-01968-2

Chen, M., Xu, L., Van Horn, L., Manson, J. E., Tucker, K. L., Du, X., Feng, N., Rong, S., & Zhong, V. W. (2025). Association of eating duration less than 8 h with all-cause, cardiovascular, and cancer mortality. Diabetes & Metabolic Syndrome: Clinical Research & Reviews, 19(7), Article 103278. https://doi.org/10.1016/j.dsx.2025.103278

Chen, Y.-E., Tsai, H.-L., Tu, Y.-K., & Chen, L.-W. (2026). Effects of timing and eating duration of time restricted eating on metabolic outcomes: Systematic review and network meta-analysis. BMJ Medicine, 5(1), Article e001071. https://doi.org/10.1136/bmjmed-2024-001071

Clavero-Jimeno, A., Dote-Montero, M., Migueles, J. H., Camacho-Cardenosa, A., Medrano, M., Alfaro-Magallanes, V. M., Osés, M., Carneiro-Barrera, A., de Cabo, R., Muñoz-Torres, M., Labayen, I., & Ruiz, J. R. (2025). Time-restricted eating and sleep, mood, and quality of life in adults with overweight or obesity: A secondary analysis of a randomized clinical trial. JAMA Network Open, 8(6), Article e2517268. https://doi.org/10.1001/jamanetworkopen.2025.17268

Cuccolo, K., Kramer, R., Petros, T., & Thoennes, M. (2022). Intermittent fasting implementation and association with eating disorder symptomatology. Eating Disorders, 30(5), 471-491. https://doi.org/10.1080/10640266.2021.1922145

Dashti, H. S., Jansen, E. C., Zuraikat, F. M., Dixit, S., Brown, M., Laposky, A., Broussard, J. L., Butler, M. P., Creasy, S. A., Crispim, C. A., Depner, C. M., Esser, K. A., Garaulet, M., Hanlon, E. C., Makarem, N., Manoogian, E. N. C., Peterson, C. M., Scheer, F. A. J. L., Wright, K. P., . . . St-Onge, M.-P. (2025). Advancing chrononutrition for cardiometabolic health: A 2023 National Heart, Lung, and Blood Institute workshop report. Journal of the American Heart Association, 14(9), Article e039373. https://doi.org/10.1161/JAHA.124.039373

Dote-Montero, M., Clavero-Jimeno, A., Merchán-Ramírez, E., Oses, M., Echarte, J., Camacho-Cardenosa, A., Concepción, M., Amaro-Gahete, F. J., Alcántara, J. M. A., López-Vázquez, A., Cupeiro, R., Migueles, J. H., De-la-O, A., García Pérez, P. V., Contreras-Bolivar, V., Muñoz-Garach, A., Zugasti, A., Petrina, E., Alvarez de Eulate, N., . . . Ruiz, J. R. (2025). Effects of early, late and self-selected time-restricted eating on visceral adipose tissue and cardiometabolic health in participants with overweight or obesity: A randomized controlled trial. Nature Medicine, 31(2), 524-533. https://doi.org/10.1038/s41591-024-03375-y

Ezzati, A., Ezzati, A., McLaren, C., Bohlman, C., Tamargo, J. A., Lin, Y., & Anton, S. D. (2024). Does time-restricted eating add benefits to calorie restriction? A systematic review. Obesity, 32(4), 640-654. https://doi.org/10.1002/oby.23984

Feit, V., Schmitz, N., Knaub, K., Schick, L. M., Mack, I., & Shojaa, M. (2026). The cross-sectional and prospective associations between time-restricted eating and cardiometabolic health in community-dwelling adults: A systematic review and meta-analysis of observational studies. European Journal of Clinical Nutrition, 80(8), 747-762. https://doi.org/10.1038/s41430-026-01755-w

Fernández-Rodríguez, R., Boira-Nacher, B., Visier-Alfonso, M. E., Torres-Costoso, A., Martínez-Vizcaíno, V., & Ruiz, J. R. (2026). Understanding participants' and health professionals' perceptions and experiences of time-restricted eating: A systematic review of qualitative evidence. Obesity Reviews, 27(5), Article e70061. https://doi.org/10.1111/obr.70061

Flynn, M. K., Parr, E. B., & Devlin, B. L. (2026). The impact of time-restricted eating on diet quality in humans: A systematic review. Nutrition Reviews, 84(3), 633-645. https://doi.org/10.1093/nutrit/nuaf301

Ganson, K. T., Cuccolo, K., Hallward, L., & Nagata, J. M. (2022). Intermittent fasting: Describing engagement and associations with eating disorder behaviors and psychopathology among Canadian adolescents and young adults. Eating Behaviors, 47, Article 101681. https://doi.org/10.1016/j.eatbeh.2022.101681

Gill, S., & Panda, S. (2015). A smartphone app reveals erratic diurnal eating patterns in humans that can be modulated for health benefits. Cell Metabolism, 22(5), 789-798. https://doi.org/10.1016/j.cmet.2015.09.005

Hamsho, M., Shkorfu, W., Terzi, M., Ranneh, Y., Varady, K. A., & Fadel, A. (2026). Early, midday, and late time-restricted eating impact on anthropometry and cardiometabolic health: A network meta-analysis of RCTs. Frontiers in Nutrition, 13, Article 1887087. https://doi.org/10.3389/fnut.2026.1887087

Hatori, M., Vollmers, C., Zarrinpar, A., DiTacchio, L., Bushong, E. A., Gill, S., Leblanc, M., Chaix, A., Joens, M., Fitzpatrick, J. A., Ellisman, M. H., & Panda, S. (2012). Time-restricted feeding without reducing caloric intake prevents metabolic diseases in mice fed a high-fat diet. Cell Metabolism, 15(6), 848-860. https://doi.org/10.1016/j.cmet.2012.04.019

He, J., Chen, X., Cui, T., Xiao, Y., Barnhart, W. R., Wang, Y., Yi, S., & Nagata, J. M. (2025). Engagement in intermittent fasting is prospectively associated with higher body mass index, higher eating disorder psychopathology, and lower intuitive eating in Chinese adults. International Journal of Eating Disorders, 58(1), 225-237. https://doi.org/10.1002/eat.24322

Hegedus, E., Vu, M. H., Salvy, S. J., Bakhsh, J., Goran, M. I., Raymond, J. K., Espinoza, J. C., & Vidmar, A. P. (2024). Randomized controlled feasibility trial of late 8-hour time-restricted eating for adolescents with type 2 diabetes. Journal of the Academy of Nutrition and Dietetics, 124(8), 1014-1028. https://doi.org/10.1016/j.jand.2023.10.012

Houston, D. K., Fanning, J., Nicklas, B. J., Delany, J. P., Hsu, F. C., Chen, S. H., Walkup, M., Neiberg, R. H., Stowe, C. L., Kennedy, K., Espeland, M. A., Ard, J. D., Miller, M. E., Rejeski, W. J., & Kritchevsky, S. B. (2026). Caloric restriction and time-restricted eating in older adults with overweight or obesity: The Health, Aging, and Later-Life Outcomes Pilot Study. The Journals of Gerontology: Series A, 81(4), Article glag061. https://doi.org/10.1093/gerona/glag061

Jamshed, H., Steger, F. L., Bryan, D. R., Richman, J. S., Warriner, A. H., Hanick, C. J., Martin, C. K., Salvy, S. J., & Peterson, C. M. (2022). Effectiveness of early time-restricted eating for weight loss, fat loss, and cardiometabolic health in adults with obesity: A randomized clinical trial. JAMA Internal Medicine, 182(9), 953-962. https://doi.org/10.1001/jamainternmed.2022.3050

Jin, X., Li, T., Xu, X., & Rong, S. (2026). The effect of time-restricted eating on sleep: A systematic review and meta-analysis. Nutrition Reviews, 84(3), 514-526. https://doi.org/10.1093/nutrit/nuaf051

Koh, J. Y. J., Tan, C. Y. H., Li, M., Liu, M. H., & Chew, H. S. J. (2025). The effectiveness of time-restricted eating as an intermittent fasting approach on shift workers' glucose metabolism: A systematic review and meta-analysis. Nutrients, 17(10), Article 1689. https://doi.org/10.3390/nu17101689

Lin, R., Wang, Y., Shuai, Z., Zhou, K., & Wu, W. (2026). Effects of time-restricted eating on body composition and performance in athletes: A systematic review and meta-analysis. Frontiers in Nutrition, 13, Article 1956159. https://doi.org/10.3389/fnut.2026.1956159

Lin, S., Cienfuegos, S., Ezpeleta, M., Gabel, K., Pavlou, V., Mulas, A., Chakos, K., McStay, M., Wu, J., Tussing-Humphreys, L., Alexandria, S. J., Sanchez, J., Unterman, T., & Varady, K. A. (2023). Time-restricted eating without calorie counting for weight loss in a racially diverse population: A randomized controlled trial. Annals of Internal Medicine, 176(7), 885-895. https://doi.org/10.7326/M23-0052

Liu, D., Huang, Y., Huang, C., Yang, S., Wei, X., Zhang, P., Guo, D., Lin, J., Xu, B., Li, C., He, H., He, J., Liu, S., Shi, L., Xue, Y., & Zhang, H. (2022). Calorie restriction with or without time-restricted eating in weight loss. New England Journal of Medicine, 386(16), 1495-1504. https://doi.org/10.1056/NEJMoa2114833

Lowe, D. A., Wu, N., Rohdin-Bibby, L., Moore, A. H., Kelly, N., Liu, Y. E., Philip, E., Vittinghoff, E., Heymsfield, S. B., Olgin, J. E., Shepherd, J. A., & Weiss, E. J. (2020). Effects of time-restricted eating on weight loss and other metabolic parameters in women and men with overweight and obesity: The TREAT randomized clinical trial. JAMA Internal Medicine, 180(11), 1491-1499. https://doi.org/10.1001/jamainternmed.2020.4153

Manoogian, E. N. C., Wilkinson, M. J., O'Neal, M., Laing, K., Nguyen, J., Van, D., Rosander, A., Pazargadi, A., Gutierrez, N. R., Fleischer, J. G., Golshan, S., Panda, S., & Taub, P. R. (2024). Time-restricted eating in adults with metabolic syndrome: A randomized controlled trial. Annals of Internal Medicine, 177(11), 1462-1470. https://doi.org/10.7326/M24-0859

Manoogian, E. N. C., Zadourian, A., Lo, H. C., Gutierrez, N. R., Shoghi, A., Rosander, A., Pazargadi, A., Ormiston, C. K., Wang, X., Sui, J., Hou, Z., Fleischer, J. G., Golshan, S., Taub, P. R., & Panda, S. (2022). Feasibility of time-restricted eating and impacts on cardiometabolic health in 24-h shift workers: The Healthy Heroes randomized control trial. Cell Metabolism, 34(10), 1442-1456.e7. https://doi.org/10.1016/j.cmet.2022.08.018

Mao, Z., Grant, H., Kritchevsky, S. B., Newman, A. B., & Farsijani, S. (2025). Association of eating window with mortality among US adults: Insights from a nationally representative study. Aging Cell, 24(11), Article e70230. https://doi.org/10.1111/acel.70230

Oldenburg, N., Mashek, D. G., Harnack, L., Wang, Q., Manoogian, E. N. C., Evanoff, N., Dengel, D. R., Taddese, A., Yentzer, B. P., Lysne, L., Wong, A., Hanson, M., Anderson, J. D., Alvear, A., LaPage, N., Ryder, J., Varady, K., Gao, Z., Ryu, S., . . . Chow, L. S. (2025). Time-restricted eating, caloric reduction, and unrestricted eating effects on weight and metabolism: A randomized trial. Obesity, 33(4), 671-684. https://doi.org/10.1002/oby.24252

Parr, E. B., Charrouf, R., Hutchison, A. T., Flint, S. A., Teong, X. T., Vincent, A. D., Bravo-Garcia, A. P., Siviour, Z., Wittert, G. A., Brennan, L., Devlin, B. L., Hawley, J. A., & Heilbronn, L. K. (2026). Time-restricted eating versus dietetic guidance on glycaemic outcomes in adults at risk of type 2 diabetes: A non-inferiority randomised clinical trial. Diabetologia, 69(9), 2458-2471. https://doi.org/10.1007/s00125-026-06762-x

Pavlou, V., Cienfuegos, S., Lin, S., Ezpeleta, M., Ready, K., Corapi, S., Wu, J., Lopez, J., Gabel, K., Tussing-Humphreys, L., Oddo, V. M., Alexandria, S. J., Sanchez, J., Unterman, T., Chow, L. S., Vidmar, A. P., & Varady, K. A. (2023). Effect of time-restricted eating on weight loss in adults with type 2 diabetes: A randomized clinical trial. JAMA Network Open, 6(10), Article e2339337. https://doi.org/10.1001/jamanetworkopen.2023.39337

Peters, B., Schwarz, J., Schuppelius, B., Ottawa, A., Koppold, D. A., Weber, D., Steckhan, N., Mai, K., Grune, T., Pfeiffer, A. F. H., Michalsen, A., Kramer, A., & Pivovarova-Ramich, O. (2025). Intended isocaloric time-restricted eating shifts circadian clocks but does not improve cardiometabolic health in women with overweight. Science Translational Medicine, 17(822), Article eadv6787. https://doi.org/10.1126/scitranslmed.adv6787

Runchey, M. C., Corapi, S., Pavlou, V., Cienfuegos, S., Lin, S., Ezpeleta, M., Gabel, K., Tussing-Humphreys, L., Oddo, V. M., Alexandria, S. J., Sanchez, J., Unterman, T., Chow, L. S., Vidmar, A. P., Reutrakul, S., & Varady, K. A. (2026). Efficacy and safety of time-restricted eating in adults with type 1 diabetes: A randomized controlled trial. Diabetes Care. Advance online publication. https://doi.org/10.2337/dc26-1093

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

Silva, A. D., Guimarães, K. C., Oliveira, R. A., Rosa, D. A., & Crispim, C. A. (2025). Time-restricted eating increases hunger in adults with overweight and obesity: A systematic review and meta-analysis of randomized controlled studies. Nutrition Research, 138, 76-88. https://doi.org/10.1016/j.nutres.2025.04.003

Skarstad, H. M. S., Haganes, K. L., Sujan, M. A. J., Gellein, T. M., Johansen, M. K., Salvesen, K. Å., Hawley, J. A., & Moholdt, T. (2024). A randomized feasibility trial of time-restricted eating during pregnancy in people with increased risk of gestational diabetes. Scientific Reports, 14(1), Article 22476. https://doi.org/10.1038/s41598-024-72913-y

Steele, C., Ostrow, A., Wang, W., Coleman, E., George, D., Bing, K., Ramanathan, S., Gregory, A., Gitomer, B. Y., Kline, T. L., Thomas, E., Chonchol, M., & Nowak, K. L. (2025). Time-restricted eating and autosomal dominant polycystic kidney disease: A pilot, randomized clinical trial. Clinical Kidney Journal, 18(4), Article sfaf069. https://doi.org/10.1093/ckj/sfaf069

Sujan, M. J., Skarstad, H. M., Rosvold, G., Fougner, S. L., Follestad, T., Salvesen, K. Å., & Moholdt, T. (2025). Time restricted eating and exercise training before and during pregnancy for people with increased risk of gestational diabetes: Single centre randomised controlled trial (BEFORE THE BEGINNING). BMJ, 390, Article e083398. https://doi.org/10.1136/bmj-2024-083398

Sun, Y., Liu, Y., Ye, W., Lebaka, V. R., Chenji, V., Li, W., & Korivi, M. (2025). Efficiency of time-restricted eating and energy restriction on anthropometrics and body composition in adults: A systematic review and meta-analysis of randomized controlled trials. International Journal of Behavioral Nutrition and Physical Activity, 22(1), Article 121. https://doi.org/10.1186/s12966-025-01812-w

Sutton, E. F., Beyl, R., Early, K. S., Cefalu, W. T., Ravussin, E., & Peterson, C. M. (2018). Early time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress even without weight loss in men with prediabetes. Cell Metabolism, 27(6), 1212-1221.e3. https://doi.org/10.1016/j.cmet.2018.04.010

Torres, L., Lee, J. L., Park, S., Di Lorenzo, R. C., Branam, J. P., Fraser, S. A., & Salisbury, B. A. (2022). Retention, fasting patterns, and weight loss with an intermittent fasting app: Large-scale, 52-week observational study. JMIR mHealth and uHealth, 10(10), Article e35896. https://doi.org/10.2196/35896

Viple, F., Pedersen, S. S., Andersen, T. H., Raben, A., Termannsen, A. D., & Salling, J. (2026). Effects of time-restricted eating on markers of glucose metabolism and regulation in individuals with prediabetes or type 2 diabetes: A systematic review and meta-analysis of randomised controlled trials. Diabetologia, 69(10), 2741-2758. https://doi.org/10.1007/s00125-026-06792-5

Vizthum, D., Katz, S. E., & Pacanowski, C. R. (2023). The impact of time restricted eating on appetite and disordered eating in adults: A mixed methods systematic review. Appetite, 183, Article 106452. https://doi.org/10.1016/j.appet.2023.106452

Wilkinson, M. J., Padilla, E., Wang, Y., Raygani, S., Manoogian, E. N. C., Laing, K., Tong, K., Liu, L., Van, D., Nguyen, J., Saltiel, A. R., Reilly, S. M., O'Neal, M., Panda, S., Majithia, A. R., & Taub, P. R. (2026). Time-restricted eating promotes weight loss and favorable changes in adipose in obesity: The TREAD randomized control trial. Obesity, 34(7), 1395-1408. https://doi.org/10.1002/oby.70228

Wu, X., Miao, J., Peng, Z., An, X., Liu, Q., Chen, L., & Liang, X. (2026). Effects of time-restricted eating on blood pressure in children: A cluster randomized controlled trial. Clinical and Experimental Hypertension, 48(1), Article 2635384. https://doi.org/10.1080/10641963.2026.2635384

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.

Rows rated with GRADE use 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.

Rows rated with CINeMA, a GRADE-based method for rating the results of a network meta-analysis, use the same 4 labels. CINeMA judges 6 domains: bias within the trials, reporting bias, indirectness, imprecision, heterogeneity, which is how much the trials disagree, and incoherence, which is disagreement between direct and indirect comparisons. The banner's rating comes from a review that used CINeMA, so the banner names that tool.

Three things about this table matter before reading it. Results against usual eating and results against daily calorie restriction are separate rows and are never combined. Every rating that the Intermittent Fasting page carries for time-restricted eating is carried here exactly, with its tool and source, and this page adds no rating of its own. Two published ratings from the same review are added for the comparison with usual eating, and one from a second review for early against late windows. The banner's outcome is body weight because weight loss is the main claim made for the pattern, and the rating describes how weight changed compared with another approach, not whether a client should aim to lose weight.

Ratings from a published review are reported exactly as that review published them. The 2026 review limited to people with prediabetes or type 2 diabetes (Viple et al., 2026) published GRADE ratings of moderate for HbA1c and for fasting glucose against a control diet without a window. Section 4 reports them as published; they are not rows in this table, because that review's population and comparisons differ from the rows below.

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, as measured: time-restricted eating against daily calorie restriction (in the banner)	Moderate that weight change was about the same	Semnani-Azad et al., 2025, using a GRADE-based method for network meta-analysis (CINeMA). Adults, mostly with overweight or obesity, in trials of 3 to 52 weeks; 14 trials compared the 2 directly, and the network adds indirect comparisons. Carried exactly as the Intermittent Fasting page carries it.	Randomized trials start high. The review found no concerns for risk of bias, reporting bias, indirectness or incoherence, and some concerns for imprecision and for heterogeneity, the variation between trials, and lowered the rating 1 level. Difference 0.39 kilograms favoring daily calorie restriction, from 1.02 favoring calorie restriction to 0.23 favoring time-restricted eating, well inside the 2-kilogram difference the review used to judge whether a change in weight matters; the review used a separate 1-kilogram bound when judging imprecision. Reported exactly as published in the review's supplementary table 5.
Body weight, as measured: time-restricted eating against usual eating with no change in eating times	Moderate for a trivial reduction	Semnani-Azad et al., 2025, using CINeMA. Same population and trial lengths; 25 trials compared the 2 directly, the largest set of direct comparisons in the review.	Randomized trials start high. The review's supplementary table 5 records some concerns for heterogeneity and no concerns for within-study bias, reporting bias, indirectness, imprecision or incoherence, and the review published the rating as moderate. Reduction 1.72 kilograms, from 1.22 to 2.21, which the review classed as trivial because it is below its 2-kilogram threshold. In the trials of at least 24 weeks, eating windows still produced a small reduction against usual eating. Reported exactly as published; this is a separate comparison from the row above and is not combined with it.
HbA1c: time-restricted eating against daily calorie restriction	Moderate for no difference detected	Semnani-Azad et al., 2025, using CINeMA. The review rated this comparison on its own, as one of 3 separate fasting comparisons; the Intermittent Fasting page carries all 3, and this page carries the time-restricted eating comparison exactly.	Randomized trials start high. Lowered 1 level, with some concerns recorded for imprecision and for heterogeneity in the review's supplementary table 13; no concerns in the other domains. This page states it as no difference detected, not as no difference.
HbA1c: time-restricted eating against usual eating with no change in eating times	Moderate for no difference detected	Semnani-Azad et al., 2025, using CINeMA. Same population; a separate comparison from the row above.	Randomized trials start high. The review's supplementary table 13 records some concerns for imprecision and for heterogeneity and no concerns in the other domains, and the review published the rating as moderate. The review's text states that no differences were noted between the fasting strategies, calorie restriction and usual eating for HbA1c; this page did not read the point estimate from the review's figure. Reported exactly as published.
Body weight, as measured: early eating windows, with the last meal before 5 p.m., against late windows, ending after 7 p.m.	High, as published, for about 1 kilogram more weight change with early windows	Y.-E. Chen et al., 2026, using CINeMA. Adults in 41 trials with a median length of 8 weeks; 2 trials compared early and late windows directly, and the network adds indirect comparisons.	Randomized trials start high. The review's supplementary table S10 records no concerns in any of its 6 domains for this comparison, so the published rating stays high. Network estimate 1.15 kilograms more reduction with early windows, from 0.45 to 1.86; the 2 direct trials alone gave 0.89 kilograms, with an interval from 1.84 more to 0.06 less, and the rest of the estimate came from indirect comparisons. The review set no threshold for an important weight difference; against the 2-kilogram threshold used by Semnani-Azad et al. (2025), this difference would be trivial. The authors wrote that their certainty ratings may be optimistic, and a later network review found no significant difference between early and late windows for most outcomes (Hamsho et al., 2026). This page carries the published label exactly and does not substitute its own.
Heart attacks, strokes, cancer incidence, progression or survival, and deaths: time-restricted eating against any comparison	Not rated	The Intermittent Fasting page's own judgment, carried exactly; that page rates none of these outcomes for any of its 3 schedules, time-restricted eating among them. No comparison could be rated.	The trials identified for this page measured risk factors, not these events. Cohort studies of usual eating hours (M. Chen et al., 2025; Mao et al., 2025) ask a different question and do not supply a treatment estimate for an eating window. A rating needs data on the outcome. This is a statement about what the searches found, not a finding of no effect and not a statement that the pattern is safe.
Eating disorder symptoms in people who practice intermittent fasting, community samples	Very low for an association, provisional	The Intermittent Fasting page's own judgment, using GRADE, carried exactly as that page carries it. Observational studies of adolescents, young adults and adults who chose to fast (Cuccolo et al., 2022; Ganson et al., 2022; He et al., 2025). The exposure is intermittent fasting as each study defined it, which includes daily fasting of about 16 hours but is not limited to time-restricted eating.	Observational evidence starts low. Lowered 1 level for risk of bias: self-selected and convenience samples, self-reported fasting and symptoms, confounding not ruled out, and 39 percent of He et al.'s participants lost by 8 months. Imprecision is also serious, but Very low is the floor. Provisional because Cuccolo et al. and Ganson et al. were available only as abstracts and He et al.'s supplement was not obtained. The Intermittent Fasting page gives every domain in full. This rates an association, not whether an eating window causes eating disorders.
Death from cardiovascular disease, usual daily eating window shorter than 8 hours against 12 to 14 hours	Very low for an association	The Intermittent Fasting page's own judgment, using GRADE, carried exactly as that page carries it. One analysis of United States survey data, 19,831 adults, eating window from 2 days of recalled eating, median follow-up 8.1 years (M. Chen et al., 2025).	This row rates the association with a usual eating window, not an intentional eating-window plan. Observational evidence starts low. Lowered 1 level for risk of bias: the window was estimated from two 24-hour recalls, and residual confounding and reverse causation remain possible, as the authors note. Imprecision is also serious: only 383 people were in the shortest-window group, with 33 cardiovascular deaths, and the hazard ratio of 2.35 has an interval from 1.39 to 3.98. A second analysis of the same survey (Mao et al., 2025) is not an independent replication. No upgrade for the large hazard ratio. Applying the finding to 16:8 as a plan would add serious indirectness, and this page does not make that transfer.

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 21, 2026, after a combined final review of the fifth batch of 5 archive pages, the repairs it asked for and a targeted recheck. Written October 19, 2026. Every rating is carried from a published review or from the Intermittent Fasting page, as the table says. What changed: After the combined final review, October 19, 2026: the TREAT trial is described as a comparison of instruction packages, with its 2021 correction; the Liu trial, the Viple review, the Runchey trial and the Spanish 3-window trial were read in full or as the authors' manuscript, and their descriptions were updated; the pregnancy and early-window passages were brought into line with their sources; and mentions of other fasting schedules were reworded. No rating label changed.

Next scheduled review: August 2027. Pages built on annual guidance are rechecked each year. The diabetes guidance cited on this page is updated every year and should be rechecked first, and the trials of early against late windows are growing quickly.

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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.