Intermittent fasting (intermittent energy restriction) is an umbrella term for meal timing schedules that cycle between periods of voluntary fasting and non-fasting over a period of time. There are various combinations/methods for that.
- Alternate day fasting: Eating for a day followed by complete (only water) or partial break for the next day and the cycle repeats till end of the voluntarily decided period.
- Daily time-restricted fasting: Eating only over a restricted time period of a day followed by fasting. For example, in 16:8 pattern, 16 fasting hours are followed by 8 non-fasting hours. Studies have shown that this diet benefits our circadian rhythm.
- Periodic fasting: Consecutive days of fasting over a week. 5:2 (two days of fast in a week) is the most commonly used pattern. Weekly 24 hour fast is also known.
Here non-fasting periods are practiced differently with or without force on caloric restriction.
Fasting periods can also have complete (water only) or partial (25% of daily calory intake) fasting.
Though studies have shown benefits of intermittent fasting on weight loss, insulin resistance, cardiovascular health, obesity, metabolic health, etc. long term sustainability of these effects is awaited. Discussion with the health care professional is required before starting any fasting methods.