Time-restricted eating: close the kitchen, eat less without counting. That's it.
16:8 is the world's favourite fasting trick. It works, mostly because a shorter day of eating means fewer chances to eat. Here's what the trials really say.
The short version
- What it is
- Eat all your food inside a daily window (8 hours in 16:8), fast the rest.
- Good for
- Eating less without counting anything. Ending late-night snacking.
- Bad at
- Beating plain old calorie cutting. The window is not a fat-burning spell.
- Evidence
- Moderate. Many trials, small effects.
- Our take
- One of our core rules. Fast as long as you comfortably can, then eat real food.
What time-restricted eating actually is
Time-restricted eating (TRE) means you only eat during a set number of hours each day. Outside that window: water, black coffee, plain tea. That's it. No points, no shakes, no app telling you that a banana is "a bit naughty".
The numbers describe the split. 16:8 is 16 hours of fasting and an 8-hour eating window, say noon to 8 pm. 14:10 is the gentle version. 18:6 and 20:4 are the hard-core versions, and at the far end sits OMAD, one meal a day. If your window sits early in the day, that's early time-restricted eating, which has its own article because the timing seems to matter.
Most of the 16 fasting hours happen while you sleep. That's why 16:8 is popular: you skip breakfast, or dinner, and call it a lifestyle.
How it works in your body
After a meal your body spends a few hours handling the incoming food: insulin goes up, sugar gets stored, fat burning takes a back seat. Once that's done, insulin drops and your body leans more on stored fat for fuel. A longer fast simply gives you more hours in that "living off your reserves" mode.
The bigger effect is much less mysterious. Fewer hours of eating usually means fewer calories. In one trial, people on a 4- or 6-hour window ate about 550 calories a day less without counting a thing, and lost about 3% of their body weight in eight weeks.4 No magic. Just a kitchen that closes.
What you eat, what you don't
Eat (inside the window)
- Protein first: eggs, fish, chicken, tofu, Greek yoghurt
- Vegetables, a lot of them
- Olive oil, avocado, nuts, seeds
- Lentils, beans, whole grains in sensible portions
- Fruit, whole, not juiced
- During the fast: water, black coffee, green or plain tea
Forget it
- "A little milk" in your coffee during the fast. It's food.
- Sugar, soft drinks, juice, in or out of the window
- Sweeteners and "zero" drinks while fasting
- Grazing all afternoon because "the window is open"
- Breaking the fast with a pastry and a latte
- Midnight snacks. The window is closed.
Alcohol on time-restricted eating
OK, now and then
- One glass of dry wine with a meal, inside the window
- Spirits with soda water and lime, with food
- A light beer with dinner
Out
- Any drink during the fast. Alcohol has calories, so it breaks it.
- Drinks on an empty stomach as the "first meal"
- Late-night rounds after the window has closed
- Cocktails, liqueurs, anything with juice or cola
50 Club: one drink with your last meal, then the kitchen and the bar close together.
While your liver handles alcohol, fat burning goes on hold: two drinks cut it by about 73% in one small study.8 Drinking into the fast undoes exactly what you fasted for. All the details are in our alcohol guide.
What time-restricted eating is good for, with proof
Eating less without counting
In a year-long US trial, people who ate only between noon and 8 pm lost about 4.6 kg more than a control group, without counting a single calorie. A group that did count calories lost about the same.3 So the window works roughly as well as counting, minus the spreadsheets. For people who hate tracking, that's the selling point.
A simple rule you can actually keep
"Don't eat after 8" is easier to remember than a meal plan. The 4- and 6-hour windows in the Chicago trial cut intake by about 550 calories a day on their own.4 That's a sandwich and a chocolate bar's worth, gone, because the kitchen was shut.
A tool, not a miracle, according to Cochrane
The 2026 Cochrane review pooled 22 trials with almost 2,000 adults. Intermittent fasting, including time-restricted eating, did about as well as regular diet advice for weight loss, with little to no difference between them.1 Read that the honest way: it's not better, it's not worse. It's another route to eating less, and the best route is the one you'll stick to.
The uncomfortable truth
"16:8 burns fat even if you eat the same." The trials disagree. In the TREAT trial, people on 16:8 for 12 weeks lost only about a quarter of a kilo more than people eating whenever they liked, and that difference wasn't statistically real.2 When a big Chinese trial gave both groups the same calorie target, adding an 8-hour window didn't make a significant difference over a year either.5
The window helps because it makes eating less easier. Eat the same amount in eight hours that you used to eat in sixteen and nothing much changes, except you're hungrier at 11 am.
"16:8 will kill you." You may have seen the headline: short eating windows linked to more heart deaths. That came from an observational study of US survey data, based on what people said they ate and when.6 It shows an association, not cause, and can't tell who was eating in a short window because they were ill, poor or working night shifts. Worth watching. Not worth panicking over.
The risks
- Muscle loss. In the TREAT trial, the 16:8 group lost more lean mass than the control group.2 Fewer meals can mean less protein. Fix: protein at every meal, and lift something heavy now and then. See our high-protein article.
- Diabetes medication. On insulin or tablets that lower blood sugar, longer gaps between meals can cause low blood sugar (hypoglycaemia). In a trial of fasting days in type 2 diabetes, the risk of hypos roughly doubled, even with reduced medication.7 Never start fasting on these drugs without your doctor.
- Eating disorders. In a large Canadian survey of 16- to 30-year-olds, intermittent fasting was linked with eating-disorder behaviours such as binge eating.9 That's a link, not proof of cause, but if food rules already run your life, a fasting window is one more rule you don't need.
- The window becomes an all-you-can-eat buffet. Very common. Fasting till 2 pm and then eating three dinners isn't a strategy.
- Hunger, headaches, grumpiness in the first one or two weeks. Usually fades. Drink water, add salt to your food, start with a shorter window.
Allergies: watch the staples
The window itself has no allergens. What you break the fast with does. Our break-fast foods lean on a few classic allergens, so we swap them if you need to.
| Break-fast staple | Allergen (EU list of 14)10 | Swap |
|---|---|---|
| Eggs | Eggs | Tofu scramble, chicken, avocado |
| Greek yoghurt, cheese | Milk | Soy yoghurt, coconut yoghurt with seeds |
| Salmon, sardines | Fish | Eggs, chicken, chia and flax for omega-3 |
| Almonds, walnuts | Tree nuts | Pumpkin and sunflower seeds |
| Tofu, edamame | Soy | Eggs, lentils, chickpeas |
| Wholegrain rye bread | Cereals containing gluten | Buckwheat, quinoa, rice cakes |
Don't do time-restricted eating if you…
- are pregnant or breastfeeding
- are under 18
- have ever had an eating disorder
- take insulin, sulfonylureas, SGLT2 drugs or GLP-1 drugs, unless your doctor plans it with you
- are underweight
- have kidney disease or another condition where meal timing matters for your medication
Healthen me asks about all of these and gives you a different plan if any apply.
How we use time-restricted eating in your plan
This is a core rule. Every plan has an eating window, and Healthen me sets it for you. You won't get a menu of 16:8, 18:6 and 20:4 to agonise over. Our message is simple: fast as long as you comfortably can.
During the fast: water, black coffee, green tea. When the window opens, your first meal is low-carb, along the lines of keto: eggs, fish, greens, olive oil. That keeps your blood sugar calm and the benefits of the fast going. The window's timing comes from chrono-nutrition: last meal about three hours before bed.
After a Rebel Day, the next day is a fasting day. If Healthen me screens you out of fasting, you get a gentle plan with regular meals instead.
This article is general information, not medical advice. If you have a medical condition or take medication, talk to your doctor before changing how you eat.
Sources
- Garegnani LI et al. Intermittent fasting for adults with overweight or obesity. Cochrane Database of Systematic Reviews 2026, Issue 2, CD015610. doi.org/10.1002/14651858.CD015610.pub2
- Lowe DA et al. 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 2020;180(11):1491–1499. doi.org/10.1001/jamainternmed.2020.4153
- Lin S et al. Time-restricted eating without calorie counting for weight loss in a racially diverse population: a randomized controlled trial. Annals of Internal Medicine 2023;176(7):885–895. doi.org/10.7326/M23-0052
- Cienfuegos S et al. Effects of 4- and 6-h time-restricted feeding on weight and cardiometabolic health: a randomized controlled trial in adults with obesity. Cell Metabolism 2020;32(3):366–378. doi.org/10.1016/j.cmet.2020.06.018
- Liu D et al. Calorie restriction with or without time-restricted eating in weight loss. New England Journal of Medicine 2022;386(16):1495–1504. doi.org/10.1056/NEJMoa2114833
- Chen M et al. Association of eating duration less than 8 h with all-cause, cardiovascular, and cancer mortality. Diabetes & Metabolic Syndrome: Clinical Research & Reviews 2025;19(7):103278. doi.org/10.1016/j.dsx.2025.103278
- Corley BT et al. Intermittent fasting in type 2 diabetes mellitus and the risk of hypoglycaemia: a randomized controlled trial. Diabetic Medicine 2018;35(5):588–594. doi.org/10.1111/dme.13595
- Siler SQ, Neese RA, Hellerstein MK. De novo lipogenesis, lipid kinetics, and whole-body lipid balances in humans after acute alcohol consumption. American Journal of Clinical Nutrition 1999;70(5):928–936. pubmed.ncbi.nlm.nih.gov/10539756
- Ganson KT et al. Intermittent fasting: describing engagement and associations with eating disorder behaviors and psychopathology among Canadian adolescents and young adults. Eating Behaviors 2022;47:101681. doi.org/10.1016/j.eatbeh.2022.101681
- Regulation (EU) No 1169/2011 on food information to consumers, Annex II (the 14 allergens). eur-lex.europa.eu/eli/reg/2011/1169/oj