How can intermittent fasting affect health?

Intermittent fasting can affect gut, liver, metabolic, hormonal, and broader health, but effects vary from person to person; overly restricted eating may disrupt reproductive hormones. 1 2

1. Gut, liver, and brown fat: Time-restricted eating has been linked to healthier gut microbiome function and may help with IBS and colitis. It has also been associated with improved liver health, including potential benefit for non-alcoholic fatty liver disease, and increased brown-fat stores. 1 3

2. Broader health effects: Fasting can promote cellular repair and clearance, and time-restricted eating may support weight maintenance or loss, blood-glucose regulation, liver health, and reduced inflammation. The discussion also describes mental clarity during fasting and possible lifespan benefits, while noting that lifespan extension remains an open question. 4 5 6

3. Reproductive hormones: If calorie intake or the eating window is restricted too much, puberty, ovulation, testosterone, and sperm counts may be affected. Leptin signaling from body fat helps signal puberty and is needed to maintain ovulation; individual responses differ, and some people may do better with meals spread through the day. 2

4. Suggested schedule: A commonly suggested starting point is an eight-hour eating window. Avoid food for at least 60 minutes after waking and stop eating two to three hours before bedtime. 7 8