Intermittent fasting window

Time restricted eating means eating within a set number of hours each day. It suits some people and not others. It starts with a few safety questions, then shows your window.

Your details

A 10 hour eating window

09:00 to 19:00

14 hours without food, mostly asleep

First meal09:00
Last meal19:00
Last meal to bedtime (23:00)4.0 hours, which matches the NHS tip for reflux of not eating in the 3 or 4 hours before bed
Days a weekevery day
Hours a week beyond a 12 hour overnight fast14 hours
Water, tea and black coffeefine at any time

In a 2022 trial of 139 adults with obesity, eating 8:00 to 16:00 plus a calorie target worked no better over a year than the same calorie target at any time. So it is one way of eating a bit less, not a magic one. If it leaves you obsessing about food, bingeing or feeling low, stop: it is not for everyone.

If food or eating feels hard to think about, Beat has a free helpline on 0808 801 0677.

The working

First meal plus your window

We add your window to your first meal. With a first meal at 09:00 and a 10 hour window, the last meal is at 19:00, leaving 14 hours without food, much of it asleep. Water, tea and black coffee are fine at any time.

If you tick any of the boxes at the top, we will not plan a window. Instead you will see why and who can help.

What the evidence says

It suits some people

A 2019 review in the New England Journal of Medicine found promising effects in animal studies and some benefits in people. Head to head trials, though, find time restricted eating works about as well as other ways of eating a little less, not better. A 12 hour window, like 08:00 to 20:00, is a gentle start that many people already do.

Who should not

When fasting is not a good idea

Under 18s, who need regular energy to grow
Pregnancy, trying for a baby and breastfeeding
Anyone with an eating disorder now or in the past
People on insulin or other diabetes medicines that can cause hypos
Anyone it leaves feeling obsessed with food, low or bingeing

Stopping is always fine. Regular meals are a perfectly healthy way to eat.

Your evening

Bedtime and days a week

Add your usual bedtime and we show the gap after your last meal. With a 09:00 start, a 10 hour window and bed at 23:00, the last meal is at 19:00, 4 hours before bed. The NHS suggests not eating in the 3 or 4 hours before bed if you get heartburn or reflux, so a window that ends earlier can help with that too.

Many people only do it on weekdays. We count the hours each week beyond a 12 hour overnight fast: a 10 hour window on 5 days is 2 × 5 = 10 hours a week. In a 2022 trial (Liu, NEJM, 139 adults with obesity), an 8 hour window plus a calorie target worked no better over a year than the same calorie target without one.

Read with care

What this cannot tell you

Medical adviceIf you have a long term condition, talk to your GP first.
Food qualityWhat you eat in the window still matters most.
AthletesHard training needs fuel around sessions.

Questions

Common questions

What is the best intermittent fasting window?

There is no best one. A 10 to 12 hour window is a gentle place to start; shorter windows are harder to stick to and not proven to be better.

Is intermittent fasting safe?

For most healthy adults it appears safe. It is not suitable for under 18s, during pregnancy, with an eating disorder history or on diabetes medicines.

Can I drink during a fast?

Yes: water, black tea and black coffee. Milky drinks contain energy.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

Please look after yourself

If food or eating feels hard to think about, Beat has a free, confidential helpline on 0808 801 0677. Your GP can help too, and it is always OK to ask.