Intermittent fasting diets involve periods of fasting cycled with periods of feeding. Fasting involves a zero or reduced calorie intake from foods and drinks. Feeding can involve food and drink consumption under strict rules – or not – and can be ad libitum (eating based on your hunger and fullness) – or not.
The term intermittent refers to the fact that the fasting periods are not continuous. Continuous “fasting” diets also exist and, conversely to intermittent fasting diets, involve energy restriction to below-“normal” requirements for continuous, prolonged periods: weeks, months, or more. Of course, you couldn’t fast continuously on zero calories, because you’d starve to death.
Intermittent fasting has been part of some health and religious practices, such as Islamic Ramadan, for thousands of years. It has been – and currently is – linked to living a longer life. (Post continues after gallery.)