Even though a 24 hour fast might make you hangry (hungry + angry), the latest research shows it also causes your guts to enhance your intestinal stem cells. These stem cells are what powers the intestine, and as people age this powerhouse starts to slow down. That’s why you gain weight easier as you grow older. The new research backs the recent craze for intermittent short fasts that celebrities take to keep off extra pounds. One of the most popular of these diets is the 5-2 diet, which allows 5 days of eating normally and 2 days of severe caloric restrictions of 600 calories or less on the fasting days.