The short version
- Intermittent fasting limits when you eat, such as 8 hours a day (16:8) or two low-calorie days a week (5:2).
- In trials, it works about as well as normal calorie cutting, not better, when calories are matched.
- It suits some people’s schedules. It is not for everyone.
The main types
| Type | How it works |
|---|---|
| 16:8 (time-restricted eating) | Eat within 8 hours, fast 16 |
| 14:10 | A gentler start |
| 5:2 | Two non-consecutive days of about 500–600 kcal, normal eating otherwise |
What the trials found
In a 2020 randomized trial (TREAT), 16:8 eating without other changes did not lead to more weight loss than eating at usual times. In a 2022 trial, time-restricted eating plus calorie restriction gave similar results to the same calorie restriction alone over a year. The takeaway: fasting can be a tool to eat less, not magic.
Try it sensibly
- Start with 12:12, then 14:10.
- Break the fast with protein and fibre: eggs, dal, yogurt, beans.
- Drink water; black coffee or plain tea are fine for most people.
- Keep strength training and protein intake up.
Who should not fast without medical advice
People who are pregnant or breastfeeding, under 18, have diabetes or take glucose-lowering medicine, or have a history of eating disorders.
If you have a health condition, take medication, are pregnant, or have a history of disordered eating, talk to your clinician before changing how you eat or train.
Common mistakes and fixes
- Overeating in the eating window. Fix: Plan protein-rich meals; the window is not a free-for-all.
- Letting protein drop. Fix: Hit your protein target across fewer meals.
- Training hard fasted and feeling faint. Fix: Eat before hard sessions or move them into your window.
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Check yourself: 3 quick questions
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Questions people ask
Does intermittent fasting burn more fat?
Trials show similar fat loss to regular calorie reduction when total intake is similar.
Can I drink coffee while fasting?
Black coffee or plain tea has almost no calories, so most fasting plans allow it.
Sources
- Lowe DA et al. Effects of time-restricted eating on weight loss (TREAT trial). JAMA Intern Med, 2020. Checked October 23, 2026.
- Liu D et al. Calorie restriction with or without time-restricted eating in weight loss. N Engl J Med, 2022. Checked October 23, 2026.
- National Institute on Aging. Research on intermittent fasting. Checked October 23, 2026.
- NIH NIDDK. Weight management. Checked October 23, 2026.
Education only. Not medical advice. Confirm with your clinician.