Many people fast for religious reasons, weight loss or metabolic health. Is it good for you? Fasting regimes include periodic one-day fasts, modified fasts involving caloric restriction and time-restricted fasts involving food restrictions during specific times during the day (religious fasts). A review of literature led by Ruth Patterson from the Department of Family Medicine and Public Health at the University of California, San Diego concluded that fasting reduced blood sugar and insulin, which are linked to chronic type 2 diabetes and heart disease, and caused some weight loss.
Fasting is not physically or mentally harmful. However, fasting causes intense hunger, so it is probably not sustainable. Fasting does not result in greater weight loss than sustained calorie-restricted dieting. We don’t 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.