You’ve probably heard the claim that exercising on an empty stomach helps boost fat loss. But is there any truth to it? While the answer depends on who you talk to (and what book you read — so many weight-loss books promote the practice), most research studies and exercise science experts agree that fasting before working out is counterproductive.
Working out on an empty stomach makes sense — in theory. Proponents say that you’ll burn more fat because your body doesn’t have carbohydrates to use as energy since you haven’t eaten. However, a February 2011 report published in Strength and Conditioning Journal found that to be untrue. Researchers found that when you don’t have proper fuel in your body, your body has less energy and therefore your exercise intensity and number of calories burned suffers. During intense workouts, your body may actually pull protein from your muscle for fuel — definitely counterproductive since muscle helps to rev metabolism.