Is fasting healthy?

Many people fast for religious reasons, for weight loss or for metabolic health. Is fasting good for you? Fasting programs include periodic fasting for one day, modified fasting that includes calorie restriction, and time-restricted fasting that includes food restrictions during certain times of the day (religious fasting).

A literature review conducted under the direction of Ruth Patterson of the Department of Family Medicine & Public Health at the University of California, San Diego, concluded that fasting lowers blood sugar and insulin levels, which are associated with chronic type 2 diabetes and heart disease, and also causes weight loss.

Fasting is neither physically nor mentally harmful. However, fasting causes intense hunger, which is why it may not be sustained. Fasting does not result in greater weight loss than a sustained calorie-restricted diet. We do not know much about the effects of fasting on sleep, hunger control or physical activity. Fasting methods that restrict nighttime eating appear to have positive long-term effects on weight control

Periodic fasting may be a good way to lose weight and promote metabolic health.

(Journal Academy Nutrition and Dietics, 115: 1203 - 1212, 2015)