I read with great interest the review article on intermittent fasting recently published in the New England Journal of Medicine. The authors start by showing that numerous studies in animals have shown increased lifespan with calorie restriction. Chronic disorders like obesity, diabetes, and cancer respond to intermittent fasting. The assumption was that calorie restriction reduces oxygen free radical production and consequently reduces cellular damage. Weight loss, however, and reduced free-radical production secondary to intermittent fasting on partly explains fasting numerous benefits. Intermittent fasting activates pathways that improves glucose regulation, increase stress resistance, and suppress inflammation. During fasting, triglycerides are converted to ketones bodies in the liver. Ketone bodies are used by organs as fuel. However, ketone bodies are not just fuel. They are signaling molecules with effect on major cellular pathways that influence health and aging. The exact mechanisms of intermittent fasting beneficial effect on our health are not fully understood. There is plenty of evidence, however, to recommend intermittent fasting for our bariatric and weight loss patients. There are a number of intermittent fasting protocols. I prefer and personally adopt daily time restricted feeding. I limit my food intake to 6 hours a day and fast for the remaining 18 hours. Others have found 5:2 intermittent fasting regimen more practical. In this regimen, calorie intake during 2 days of the week is restricted to 500 calories a day.

The authors conclude that combined with exercise, intermittent fasting results in many long-term adaptations that improve “mental and physical performance and increase disease resistance”.