Is Cardio Good To Do On An Empty Stomach?

Your body is much like the gas tank in your car -- you need to provide it with fuel, in this case food, to keep it functioning properly. However, when you are exercising to lose weight, working on an empty stomach can cause your body to focus less on burning calories and more on the fat you are hoping to lose. This effect of an empty stomach can come with a few difficulties -- you may not have enough energy to complete an exercise session without eating first, or your body may start to take nourishment from other important areas, like your muscles.

Research

Researchers at the England's University of Birmingham established a link between fat burning and cardiovascular exercise in a 2010 study published in "Medicine & Science in Sports & Exercise." The researchers measured the fat-burning effects of eating versus not eating before exercise on young, healthy cyclists. One group would engage in an hourlong exercise session without eating beforehand, while the other had a small meal before exercising. The researchers found athletes who exercised on an empty stomach burned more fat than those who ate before exercising.

Study Note

While the University of Birmingham study did find that you burn fat faster when performing cardiovascular exercise on an empty stomach, there are some caveats to consider. The first is that the amount of fat may not be statistically significant enough to translate into a large weight-loss difference. If you are training frequently, however, the difference may be enough to experience an increase in your fat-burning capabilities with regular exercise.

Fat Burning/Muscle Loss

Although eating on an empty stomach may help you burn fat more efficiently, you also may burn through some of your lean muscle mass. If you are exercising first thing in the morning, the lack of protein after you sleep and while exercising can cause your body to burn lean muscle mass. This is problematic because lean muscle mass burns more calories than fat and can affect your metabolism and how many calories you are able to burn while at rest. To reduce the likelihood that you will lose muscle mass, consume a 200- to 300-calorie snack 30 to 45 minutes before your exercise session. Snacks can include egg whites, cottage cheese, yogurt or a small bagel with peanut butter.

Expert Insight

While cardiovascular exercise on an empty stomach may help you burn fat, your body may not respond well during workouts. "That might help you get very good at burning fat, but you won't be very good at whatever exercise it is you're doing," Ron Maughan, an exercise science professor at Loughborough University in England, said to the Associated Press. "Without enough fuel, you won't get the intensity of training you need to get improvements."