Answer from Michele Stanten, Prevention‘s Fitness Director
Yes, but don’t expect any fat-melting miracles. When you exercise, your body burns both fat and carbohydrate calories. Recent studies show that working out on an empty stomach might burn a few more fat calories than when you work out an hour or two after eating–but total calorie burn is about the same.
And, based on research so far, that’s what really counts when it comes to fitting into a smaller size. What scientists don’t yet know is whether an increase in fat burn alone could help you lose weight faster or shed more pounds over time. So the choice about when to eat is yours.
I’ve found I can do my 30- to 45-minute walks on an empty stomach no problem, but I need to fuel up before longer bike rides with my husband. To determine what’s right for you, try this experiment: Eat a snack of about 200 calories–like a banana with peanut butter, whole grain crackers and low-fat cheese, or an energy bar–1 to 2 hours before you exercise, then note how you perform.
How long can you go before you feel tired? Can you pick up the intensity? The next day, work out without eating and note any differences. Exercising on an empty stomach can backfire by decreasing your calorie burn if you’re too tired to complete your workout or slack off during it.