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Time-restricted5 studies in people cited

14:10 Time-Restricted Eating

14 hours without food · Daily

Written by Reviewed Sep 2026

Also called: 10-hour eating window, Personalised TRE

You eat inside a 10-hour window, usually cut down from a normal eating day of 14 hours or more. In people who already had blood sugar or heart health problems, this window had the strongest results on those markers. It is also the window where the most weight lost came from fat, not muscle.

Overview

Most studies of the 10-hour window come from two groups in California: the Panda group at the Salk Institute and Wilkinson at the University of California San Diego. They studied adults with metabolic syndrome or obesity who ate across 14 hours or more a day before they started. For those people this is not really a fast. It is eating over a day that is 4 hours shorter.

Keep that in mind when you read the results. In the TIMET study, people started out eating across 14.19 hours a day. They had to cut that by at least 4 hours. They did it by starting to eat 1 hour 49 minutes later after waking up and stopping 2 hours 50 minutes earlier before bed. Both ends moved.

In the studies, this window gave a small drop in long-term blood sugar (HbA1c). It gave a clear drop in blood sugar swings. Most of the weight people lost was fat. Blood pressure and LDL cholesterol also improved. These people were already on statins and blood pressure pills, and they stayed on them.

How it works

Pick a 10-hour window you can keep the same every day, and log everything with calories. TIMET let each person pick their own window instead of giving everyone the same clock time. The only rule was to cut at least 4 hours from their usual eating day. People logged meals as they ate them in the myCircadianClock app. Wilkinson's earlier study, which had no comparison group, had people pick their own 10-hour window and keep it steady.

People stuck with it well in both, and this was measured, not guessed. In TIMET, 11.6% of days had some calories more than 15 minutes outside the window, so people were on plan more than 85% of days. In the 2020 study, people logged 85.61% of the time.

In TIMET, people kept taking their medicines. The window was tested as something added on top of normal care, not in place of it.

What 14 hours actually reaches

At 10 hours, studies measured a small effect on blood sugar and a bigger effect on blood sugar swings. In TIMET, long-term blood sugar (HbA1c) fell 0.10% more than with normal care. It started at 5.87%. Glucose monitors worn on the body showed blood sugar swings within a day fell 7.7% and swings from day to day fell 14.1%, compared with normal care. Those were the biggest differences in the study. A 14-hour fast is the shortest one on this site and does the least. Nobody has measured autophagy or mitophagy (the cell's clean-up of old parts) in a person on a 10-hour eating window. Nothing supports talking about this window as crossing some cell clean-up line. What it does change, going by what has been measured, is blood sugar overnight and in the morning, and blood pressure. The fair comparison is the 12-hour window. In these studies the 12-hour window is usually the comparison, not the plan being tested. One real-world study gave 54 adults a 12-hour window for 6 months. They lost 1.6% of their weight. People given normal diet advice lost 1.1%. The 0.88% gap was too small to count as a real difference.

Fig. 1 · what has been measured, hour by hour
  1. 0h to 4h

    Still digesting

    Burning
    Sugar from the meal you just ate. Insulin is high enough to keep fat locked away.
    • Insulin is at its after-meal peak. While it is up there, the enzyme that releases fat from fat cells stays switched off, so fat is being stored, not released.
    • The hour count on most fasting charts starts at the last bite. But the body is still digesting a mixed meal here, so the clock and what the body is doing are not yet the same thing.

    Read the biologyInsulin and insulin sensitivity during a fast

    Measured in people
    The hour-by-hour fasting studies in people start later than this. Klein 1993 took its first sample at 12 hours, in 6 healthy men. Rothman 1991 gives its first figure for new sugar making as an average across the first 22 hours. This row is the fed state those measurements are compared against. No measurement from a long fast falls inside it.

  2. 4h to 12h

    Meal digested, overnight fast

    Burning
    A mix of leftover sugar and fat. The liver keeps the brain supplied with sugar.
    Blood sugar
    5.58 mmol/L (100.5 mg/dL) at the 12 hour mark, in 6 healthy men
    Ketones
    Total ketones around 0.20 mmol/L after an overnight fast. That figure is acetoacetate and BHB added together, not BHB on its own.
    Insulin
    64.6 pmol/L (9.3 microunits/mL) at 12 hours, in the same 6 men
    • At 12 hours, glycerol is released at 2.08 and palmitic acid at 1.63 micromol/kg/min. These are two markers of fat being released. They are the starting numbers everything later in the fast is compared against.
    • Making new sugar from scratch already supplies most of the body's sugar at this point. It is not a backup waiting to be called on. This is the first place the popular "switch" story breaks down.

    Read the biologyInsulin and insulin sensitivity during a fastGlycogen depletion and gluconeogenesis

    Measured in people
    Klein 1993 measured blood sugar, insulin and fat release with tracers at 12 hours, in 6 healthy men. Féry 1983 measured total ketones in people after an overnight fast and put the starting level at 0.20 mmol/L. Rothman 1991 measured liver glycogen again and again with a special MRI scan through a 68 hour fast in healthy adults. It worked out that new sugar making supplied 64% of all the body's sugar across the first 22 hours.

  3. 12h to 18h

    Ketones have not moved yet

    Burning
    Fat use rising. More and more of the body's sugar is being made fresh, not pulled from storage.
    Ketones
    A middle change of 0% between 12 and 18 hours, measured every 6 hours in 34 adults
    • BHB, the main ketone, does not move in this window. In 34 adults sampled every 6 hours through the standard 72 hour fast doctors use for testing, the middle change from 12 to 18 hours was zero.
    • Making new sugar supplies 64% of the body's sugar across the first 22 hours. A second, unrelated method put it at about 47% by 14 hours. The body does not switch from stored sugar to fat at a set hour.
    • In 11 overweight adults, activity of the autophagy gene LC3A in blood cells was 22% higher after an 18 hour fast than after a 12 hour fast. In the same people, activity of the MTOR gene also rose, by 9%.

    Read the biologyGlycogen depletion and gluconeogenesisKetogenesis and beta-hydroxybutyrateAutophagy

    Measured in people
    Service 2005 measured BHB every 6 hours in 34 adults whose 72 hour test fasts came back clear for a rare insulin-making tumour. Rothman 1991 measured the share of new sugar making with a special MRI scan. Jamshed 2019 measured gene activity in blood cells in an 11-person, 4 day study where each person tried two eating windows: 8am to 2pm, and 8am to 8pm. That is one gene's activity in blood cells. It is not the real speed of autophagy, and it is not muscle. No study in any species has tested a 16 hour time point for autophagy.

  4. 18h to 1d

    The biggest hours for fat release

    past this window
    Burning
    Fat and glycerol, with ketone making starting its climb
    Ketones
    Climbing. The middle rise from 18 to 36 hours was +333%, the steepest stretch of a 72 hour fast.
    Insulin
    70% of the whole drop seen across a 72 hour fast has already happened by 24 hours
    • The single biggest jump in fat release across a whole 72 hour fast comes between 18 and 24 hours. 60% of the total rise in fat release happens between 12 and 24 hours. The authors put that down to falling insulin, not to any change in blood sugar.
    • In a study of 30 healthy adults, growth hormone was clearly higher after a 24 hour water-only fast than after a normal eating day. Each person did both. The size of that rise is not in the published summary, so it is not given here.
    • In the same study, haemoglobin, red blood cell count and haematocrit all rose together at 24 hours. That pattern means the fluid part of the blood shrank. It does not mean new red blood cells were made.
    • In 20 volunteers, energy burned over 24 hours, measured in a sealed room, fell during a 24 hour fast. How much it fell varied from person to person.

    Read the biologyInsulin and insulin sensitivity during a fastThe growth hormone responseKetogenesis and beta-hydroxybutyrateAutophagy

    Measured in people
    Horne 2013 had 30 seemingly healthy adults do both a 24 hour water-only fast and a normal eating day, in random order. It measured growth hormone, blood counts, cholesterol, triglycerides, bicarbonate and weight. Klein 1993 measured fat release with tracers. Hollstein 2020 measured energy burned over 24 hours in a sealed room in 20 volunteers. The exact percentage drop is not in the published summary, so it is not given here. On autophagy, a 24 hour fast raised p62 (also called SQSTM1) in the thigh muscle of 50 women. That points toward less recycling in muscle, not more.

  5. 1d to 36h

    Thyroid drops before metabolic rate does

    past this window
    Burning
    Fat. The remaining sugar is built from glycerol, lactate and protein building blocks.
    Ketones
    1.308 mmol/L on average after day 1, in 13 men starting a 10 day water fast, up from 0.177 at the start. People varied a lot: the spread around that average (1.053) was nearly as big as the average itself.
    • Making new sugar supplies 82% of the body's sugar between 22 and 36 hours.
    • In 8 healthy men, the thyroid hormone T3 fell from 2.30 to 1.84 nmol/L by 30 hours. TSH, the hormone that tells the thyroid to work, fell below 1 mU/L, and its usual night-time peak disappeared. Blood cortisol did not change.
    • So the thyroid slows down within the first 30 hours, well before anyone can measure a drop in resting metabolic rate.
    • Salt loss has not turned yet. In 9 women with obesity who kept eating their usual amount of salt while fasting, salt in the urine started to rise after about 48 hours and then went above what they took in.

    Read the biologyGlycogen depletion and gluconeogenesisKetogenesis and beta-hydroxybutyrateAutophagy

    Measured in people
    Rothman 1991 measured the share of new sugar making with a special MRI scan in healthy adults. Hugues 1984 fasted 8 healthy men for 30 hours and tested their thyroid hormones again and again. Dai 2022 measured blood BHB daily in 13 men fasting in a supervised facility. Sigler 1975 collected urine in 3 hour blocks from 9 women with obesity on a hospital ward. On autophagy, the only study in people with several time points in one fast took thigh muscle samples at 2, 12, 24 and 36 hours. The markers LC3I, LC3II and p62 all fell, but only in untrained people. The authors sum it up as muscle recycling being only mildly affected by 36 hours of fasting.

What studies in people found

There is one study in people with metabolic syndrome that looked mainly at long-term blood sugar, and one in people with obesity that looked mainly at weight. An earlier small study with no comparison group led to both. All three measured how well people stuck with it directly, instead of only asking them to remember.

  • The TIMET study (Manoogian 2024), 121 people for 3 months (108 finished). They were adults with metabolic syndrome and high fasting blood sugar or high long-term blood sugar. Everyone got normal diet coaching and kept taking their medicines. Long-term blood sugar (HbA1c) fell 0.10% more than with normal care. The window group lost 2.98 kg and the normal-care group lost 1.32 kg, a gap of 1.66 kg. The bottom blood pressure number fell 3.98 mmHg in the window group, and LDL cholesterol fell compared with normal care. There were no major side effects.
  • The TREAD study (Wilkinson 2026), 61 adults with obesity for 12 weeks (52 finished). All had been eating across 14 hours or more a day. The window group lost 4.59 kg. The group given normal diet coaching lost 1.68 kg, a gap of 2.91 kg. Most of the loss was body fat. Researchers also tested genes in belly fat taken with a needle. Genes linked to inflammation were turned down. That is a clue about how it might work, not a health result.
  • Wilkinson 2020, 19 people with metabolic syndrome for 12 weeks (35 started). There was no comparison group. Most were on a statin, a blood pressure pill or both. Weight fell 3.3 kg. The top blood pressure number fell 5.12 mmHg and the bottom number fell 6.47 mmHg. LDL cholesterol fell 11.9 mg/dL and total cholesterol fell 13.2 mg/dL. Long-term blood sugar fell 0.14% across the group, which was not clearly real. In the 12 people who started at 5.7% or above, it fell 0.22%. With no comparison group, all of this is change within the same people while they stayed on their normal medical care.
  • Glucose monitors in TIMET: blood sugar swings within a day were 7.7% smaller in the window group than in normal care. Swings from day to day were 14.1% smaller. That is the biggest blood sugar swing result in the eating window studies.

What this does not tell you: TIMET ran 3 months and TREAD 12 weeks, so neither tells you if the results last. What people ate was self-reported in both. TIMET's drop in long-term blood sugar was 0.10% from a level that was already close to normal. It is a real result and a small one. The 2020 study had no comparison group at all. TIMET checked body make-up as a side question in the 108 people who finished. It was not built to answer that question.

Reading the research record

The 10-hour window sits in an awkward spot in the fight over whether eating windows do anything beyond cutting calories. In these studies, the comparison group got normal diet coaching, not the same calorie target. TIMET and TREAD both beat normal care. Neither tested the window against an equal calorie cut. That kind of test is the one that found no extra benefit for an 8-hour window in Liu 2022.

There is also a real disagreement about whether shorter is better. Cienfuegos 2020 found 4-hour and 6-hour windows gave the same weight loss. That hints that each extra hour of fasting stops paying off at some point. In Oldenburg 2025, people told to keep an 8-hour window of their choosing drifted out to 9.8 hours and did no better than people who ate freely. Meanwhile TIMET's 10-hour window clearly beat normal care in people who started at 14.19 hours. Put together, results seem to track how much people cut from their usual eating day more than the exact length of the window. No study has been set up to test that directly.

The research groups behind these studies also signed a published reply to a US health survey study (NHANES) on eating-window length and death, which the 5:2 and alternate-day pages discuss. Several of them list ties to industry in that paper. That is useful context for reading the field. It is not a reason to throw out their measurements.

What happens to muscle

TIMET had the best split between fat and lean mass lost in this field, and said so plainly. Lean mass means the non-fat part of you, mostly muscle and water. The window group lost 2.98 kg on average. About 2.24 kg of that, around 75%, was fat. Only about 0.28 kg, around 9%, was lean mass. Total fat fell 6.7%. The window group lost 1801.11 g more fat than the normal-care group. The authors pointed out that this is the opposite of studies where people on eating windows lost too much lean mass.

That 9% sits at the other end from TREAT, where about 65% of the weight lost on an 8-hour window was lean mass. Both used body scans, both looked at this as a side question, and neither study was built to answer it. TREAT measured 50 people over 12 weeks. TIMET measured 108 over 3 months.

The two differences most likely to matter are who took part and how long the window was. TIMET's people were 59 on average, had metabolic syndrome, and were cutting a 14-hour eating day by 4 hours. TREAT's people were younger and cut much further, and nobody measured their protein. The protein research points the same way every time. Studies that fed 1.6 to 2.2 g of protein per kg of body weight a day and had people lift weights kept lean mass, whatever the window. The one study at 1.0 g per kg a day lost more. Neither TIMET nor TREAT reported protein per kg of body weight, so this fits the studies but was not tested by them.

Doing it

Measure your current window first
TIMET asked people to cut at least 4 hours from their usual eating day, and they started at 14.19 hours. If you already eat across 11 hours, you are doing something different from someone who starts at 15.
Log it, do not estimate it
Both Salk group studies had people log meals in an app as they ate, and measured how well they stuck with it. In studies where people picked a window and did not log, the window drifted. In Oldenburg's study, an 8-hour window turned into 9.8 hours.
Protein target
Neither TIMET nor TREAD reported protein per kg of body weight. Across the wider research, people kept lean mass in studies with 1.6 to 2.2 g per kg a day. In the one study at 1.0 g per kg a day, they lost more. So protein is the number worth tracking inside a 10-hour window.
Medication stays
In TIMET people kept taking their medicines, so its results show what a window adds on top of normal care. Blood pressure pills matter most here. Fasting already lowers blood pressure, because insulin drops, the body sheds salt, and it lets go of water stored with sugar in the muscles and liver. The pills add to that.
Where the strongest signal was
Blood sugar swings, not weight. Glucose monitors showed swings 7.7% smaller within a day and 14.1% smaller from day to day compared with normal care. Along with long-term blood sugar, these were the biggest changes in TIMET.

Breaking the fast

A 14-hour overnight fast ends the normal way, and no study here set a first meal. Here is the useful science. In healthy adults who have not eaten recently, muscle building ticks along at about 0.03 to 0.05 %/h, and this is the same in young and old people. So an overnight fast has not switched muscle building off. It has only removed the boost that eating gives. Older adults need more protein per meal to get that boost. In men around 71, 40 g beat 20 g after exercise.

Sources

  1. Study in people2024
    Time-Restricted Eating in Adults With Metabolic Syndrome: A Randomized Controlled Trial

    Annals of Internal Medicine

    121 adults with metabolic syndrome spent 3 months on an 8 to 10 hour eating window plus usual care, or usual care alone. The window group lost 2.98 kg against 1.32 kg, and about 75% of the weight lost was fat. Long-term blood sugar dipped 0.10% and swung less from day to day. People kept the window on more than 85% of days, with no major side effects.

    121 randomised, 108 completed, 3 months of personalised 8 to 10 hour eating plus standard-of-care counselling versus standard of care alone in metabolic syndrome. HbA1c -0.10% (95% CI -0.19% to -0.003%). Weight -2.98 kg versus -1.32 kg, between-group -1.66 kg. Of that loss, 2.24 kg (about 75%) was fat and 0.28 kg (about 9%) lean. CGM intra-day variability -7.7% and inter-day -14.1% between groups. Adherence above 85% of days. No major adverse events.

  2. Study in people2026
    Time-Restricted Eating Promotes Weight Loss and Favorable Changes in Adipose in Obesity: The TREAD Randomized Control Trial

    Obesity (Silver Spring)

    61 adults with obesity who normally ate over 14 hours or more a day tried a 10-hour window or usual diet advice for 12 weeks. The window group lost 4.59 kg against 1.68 kg, and most of it was body fat. Fat tissue samples showed genes linked to inflammation turned down, but that was an extra look, not the main question. 52 people finished.

    61 randomised, 52 completed, 12 weeks of a 10-hour window versus standard-of-care dietary counselling in adults with obesity and a baseline window of 14 hours or more. Weight -4.59 kg (95% CI -5.51 to -3.67) versus -1.68 kg, between-group -2.91 kg (P < 0.001), loss primarily body fat. Exploratory adipose RNA sequencing showed downregulation of proinflammatory genes.

  3. Study in people2020
    Ten-Hour Time-Restricted Eating Reduces Weight, Blood Pressure, and Atherogenic Lipids in Patients with Metabolic Syndrome

    Cell Metabolism

    35 people with metabolic syndrome started a 10-hour eating window for 12 weeks, and 19 were counted. There was no comparison group. Weight fell 3.3 kg, blood pressure fell, and LDL (bad) cholesterol fell 11.9 mg/dL. Long-term blood sugar barely moved overall, but fell 0.22% in the 12 people who started at 5.7% or higher.

    Single-arm, not randomised. 35 enrolled, 19 analysed, 12 weeks. Weight -3.3 kg, systolic -5.12 mmHg (P = 0.041), diastolic -6.47 mmHg (P = 0.004), LDL -11.9 mg/dL, total cholesterol -13.2 mg/dL. HbA1c -0.14% overall (P = 0.058) and -0.22% (P = 0.04) in the 12 participants with baseline HbA1c at or above 5.7%. Logging adherence 85.61%. No control arm.

  4. Study in people2021
    The Effects of Time-Restricted Eating versus Standard Dietary Advice on Weight, Metabolic Health and the Consumption of Processed Food: A Pragmatic Randomised Controlled Trial in Community-Based Adults

    Nutrients

    54 adults who ate over more than 14 hours a day and had at least one sign of metabolic syndrome tried a 12-hour window or standard diet advice for 6 months. The window group lost 1.6% of body weight and the advice group 1.1%. The gap between them was too small to count as a real difference. It shows how little a 12-hour window does on its own.

    54 adults with a baseline eating duration above 14 hours and at least one metabolic syndrome component, 6 months of a 12-hour window versus standard dietary advice. TRE lost 1.6% of initial body weight (SD 2.9, p = 0.01) and standard advice 1.1% (not significant), with a between-group difference of 0.88% that was not significant (p = 0.43). The reference point for how little a 12-hour window moves on its own.

  5. Study in people2020
    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

    Cited here for what happens to muscle. In 50 people who got body scans, an 8-hour window lost 1.70 kg, and about 65% of it (1.10 kg) was lean mass. A 10-hour window in another study, TIMET, lost only about 9% as lean. Neither study was built to answer the muscle question.

    Cited here as the lean mass counterpoint. In the 50-person DXA subgroup an 8-hour window produced 1.70 kg of weight loss of which 1.10 kg was lean mass, approximately 65%, against TIMET's approximately 9% at a 10-hour window. Both were DXA, both secondary outcomes, neither powered for body composition.

What people report

These are things people say about their own fasting. Nobody checked them, so they are not evidence. They are here because they tell you what to expect and what to watch for, which the studies do not. They cannot tell you whether anything works.

  • Easier to keep up than a shorter window, because you still get breakfast.
  • Both ends of the day moving, a later start and an earlier finish, not just one.
  • Better sleep timing as the last meal moves further from bedtime.
  • A small early weight drop that keeps going slowly instead of stopping.

Sources: These are self-reports with no comparison group. They are habits and impressions people logged inside the studies on this page. That includes the measured 1 hour 49 minute later start and 2 hour 50 minute earlier finish in TIMET. They are not survey data. A separate review of what fasting communities report is still being put together, and nothing here comes from it.

Who this is wrong for

  • Anyone taking an SGLT2 inhibitor, unless a prescriber stops it first. It can cause ketoacidosis (a dangerous acid build-up) while blood sugar looks normal.
  • Anyone on insulin, a sulfonylurea or a meglitinide whose dose has not been checked against a shorter eating day.
  • Pregnancy and breastfeeding. The body needs sugar all day long. In 18 reported cases of ketoacidosis while breastfeeding, dieting to lose weight set off 76% of them.
  • Anyone with a past eating disorder, or who now has episodes of eating they cannot control.
  • Children and teens. There are no long-term studies on growth or development.
  • Anyone with a BMI under 18.5, or who meets the UK NICE risk list for refeeding problems.
  • Anyone whose work hours make a steady window impossible. Keeping the window steady, more than keeping it short, is what these studies actually delivered. A study of 10-hour windows in shift workers is running at the Salk Institute. Its main results are due in August 2028.

Questions

Is a 10-hour window long enough to do anything?
In people who were eating across 14 hours or more, yes, and it can be measured. TIMET lowered long-term blood sugar (HbA1c) by 0.10% more than normal care. It cut blood sugar swings within a day by 7.7% and from day to day by 14.1%. People lost 1.66 kg more weight over 3 months. TREAD gave 2.91 kg more weight loss than diet coaching alone over 12 weeks. Nobody has tested whether the same window helps someone who already eats across 11 hours.
Why did this window preserve lean mass better than shorter ones?
In TIMET, about 9% of the weight lost was lean mass. In TREAT, on an 8-hour window, it was about 65%. But the studies also differed in who took part, how long they ran, and protein that nobody measured, not just window length. The protein research points at protein, not the window. Studies at 1.6 to 2.2 g of protein per kg of body weight a day kept lean mass at 8 hours. The one at 1.0 g per kg a day did not. Neither TIMET nor TREAD reported protein per kg of body weight.
Does it matter where in the day the 10 hours sit?
TIMET let people pick their own window instead of setting a clock time. People moved both ends: they started 1 hour 49 minutes later after waking and stopped 2 hours 50 minutes earlier before bed. A separate study had 15 men try both an early and a late 9-hour window. It found no difference between the two on anything measured. Only the early window lowered average fasting blood sugar compared with where those men started.