Types of fasting

Intermittent fasting is an umbrella term for diets that cycle between a period of fasting and non-fasting during a defined period. It can be grouped into two categories: whole-day fasting and timerestricted feeding.

Whole-day fasting involves regular one-day fasts. The strictest form is alternate-day fasting. This involves a 24-hour fast followed by a 24-hour non-fasting period. The well-known 5:2 diet allows the consumption of 500-600 calories on two fasting days in a seven-day cycle.

Time-restricted feeding, on the other hand, involves eating only during a certain number of hours each day. A common form involves fasting for 16 hours each day and only eating during the remaining eight hours, typically on the same schedule each day. A more liberal practice would be 12 hours of fasting and a 12- hour eating window, or a stricter form would be to eat one meal per day, which would involve around 23 hours of fasting per day.