Weight-Loss Q&A: Eating Before Exercising
Q: My husband says you should never eat two hours before or after you exercise. I say the rule is one hour. Who's right?
A: "Neither of you," says Bonnie Modugno, M.S., R.D., a nutrition consultant in private practice in Santa Monica, Calif.
When you should eat before a workout depends on how hard you'll be exercising, how long you'll be exercising, how long it has been since your last meal and your individual tolerance for having food in your stomach. "If you're going to exercise intensely, waiting a couple of hours is a good idea so that you get the food out of your stomach and into your intestines," Modugno says. That's because blood flow gets shifted to your abdomen while your body digests a meal, leaving less blood available to deliver oxygen to your exercising muscles. On the other hand, if you haven't eaten for several hours before a workout, you may need a snack -- such as a banana, a glass of lowfat milk, some yogurt or even half a sandwich -- an hour or half-hour before you exercise. "You don't want to feel hungry and weak," Modugno says.
After you exercise, the sooner you eat, the better. If you wait too long, you're likely to become lightheaded and ravenous, in which case you'll probably end up overeating. For athletes who do double workouts -- say, one workout within six hours of another -- it's important to refuel immediately. The body is most sensitive to replenishing glycogen stores right after activity and becomes less sensitive as the hours pass. Glycogen is the form of glucose (blood sugar) that is stored in your muscles, readily available for energy when you exercise. If you won't be exercising until the next day, eating right away isn't crucial because 24 hours is plenty of time to replenish your glycogen. Still, you'll feel better if you eat soon after a workout.