Intermittent fasting (IF) describes eating patterns that alternate between periods of fasting and eating. The main approaches:
Fast for 16 hours, eat within an 8-hour window. Most commonly: skip breakfast, eat midday to 8pm. The most popular approach — much of the fast happens during sleep.
Fast for 18 hours, eat within a 6-hour window. More restrictive than 16:8, typically eating 1pm–7pm.
Eat normally five days per week. On two non-consecutive days, restrict to 500 calories (women) or 600 calories (men). Created and popularised by Dr Michael Mosley.
A 23:1 fast — eat all daily calories in one meal. The most extreme common approach; effective for some but difficult to sustain socially.
Track your fasting with our free intermittent fasting tracker.