Confusing Fitness Advice, Decoded

Should You Work Out On An Empty Stomach?

The Confusion We know that food fuels us. But if you’re looking to lose weight, some people—possibly those who read the 1999 bestseller Body for Life—believe exercising with a growling tummy may help burn fat faster. “The rationale behind this theory is that low glycogen levels cause your body to shift energy utilization away from carbohydrates toward fat,” says Keri Peterson, MD, a medical contributor to HealthiNation.

The Reality This theory holds no weight in the scientific community. “Results of studies show that with low-intensity to moderate exercise, fat burning remained the same for up to 90 minutes in both fasting and non-fasting subjects,” says Dr. Peterson. Need further proof? Working out with or without food in your tummy won’t affect the amount of fat you torch—but not eating before working out may cause muscle loss if you do it regularly, according to the February 2011 issue of Strength and Conditioning Journal.

The Bottom Line When your body is famished, it kicks into survival mode and starts using muscle—like those abs you’ve been working on—as a source of protein. Do your bikini body a favor and make sure you have a light meal or sports drink to raise your blood sugar before exercise.

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