Intermittent fasting (intermittent energy restriction or intermittent calorie restriction) is an umbrella term for various eating protocols that cycle between a period of fasting and non-fasting over a defined period. Intermittent fasting is under preliminary research to assess if it can produce weight loss comparable to long-term calorie restriction.
Fasting is the willing abstinence or reduction from some or all food, drink, or both, for a period of time. An absolute fast or dry fasting is normally defined as abstinence from all food and liquid for a defined period. Water fasting refers to abstinence from all food and drink except water, but black coffee and tea may be consumed. Other fasts may be partially restrictive, limiting only particular foods or substances, or be intermittent.