Exercising on an Empty Stomach Can Burn More Body Fat

November 7, 2010 Updated: October 1, 2015

EXERCISE: Studies suggest that exercising while having little food in the stomach is a good choice for burning fat. (Franck Fife/AFP/Getty Images)
EXERCISE: Studies suggest that exercising while having little food in the stomach is a good choice for burning fat. (Franck Fife/AFP/Getty Images)
In most cases, people who exercise, do it to lose weight or build muscle. In general, people who want to burn fat, eat foods low in carbohydrates and fast before exercising, while those who want to increase muscle mass, eat food with more carbohydrates and eat before exercising.

But do you really burn more fat while exercising on an empty stomach? Some think that by fasting before exercise, they will gain weight because the body activates a metabolic alert, increasing the desire to eat.

Several studies suggest that exercising while having little food in the body, is a good choice for burning fat. In a recent study, published in April, researchers at the University of Birmingham and other institutions studied seven people who exercised intensively while fasting and seven others who exercised after eating.

At the end of the study, researchers found that the group of seven people who exercised on an empty stomach burned more body fat than the group of seven people who trained after eating.

Peter Hespel, professor of exercise physiology at the University of Leuven, Belgium, says that when an athlete fasts, no carbs are available, adrenaline is high, and insulin is low, so the muscles oxidize or dissolve reserve fatty acids.

The researchers also found that exercising on an empty stomach produces lower physical performance, which implies that it is a bad choice for athletes who want to achieve greater physical performance, but it is a good choice for those who want to lose fat.

The results were published in Medicine and Science in Sports and Exercise, the official journal of the American College of Sports Medicine.