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How long after eating can I exercise?

The best time to work out is before you eat, experts say. But if you need an energy boost, here's what to reach for.
A 100-200 calorie sports bar is a smart snack if you need an energy boost before a workout.
A 100-200 calorie sports bar is a smart snack if you need an energy boost before a workout.TODAY Illustration / Getty Images stock
/ Source: TODAY

You want to have enough energy to get in an after-lunch workout, but worry that a meal might make you nauseous. Is it OK to exercise after you eat, or should you fast until your workout is over?

It depends.

For many people, exercising strenuously on a full stomach can lead to reflux, hiccups, nausea and vomiting, said Dr. Daniel Vigil, associate clinical professor of family medicine and orthopaedic surgery at the David Geffen School of Medicine at the University of California, Los Angeles. But there are some people who can eat a big meal and experience no issues when they exercise afterward, Vigil said.

Research, on the other hand, shows that eating before exercising is not ideal. The best time to work out, Vigil said, is before you eat. A post-exercise nutrition program helps recovery and minimizes muscle damage, Virgil said. Plus, a study published in The American Journal of Physiology found that men who exercised without eating beforehand burned more fat.

However, if your schedule demands you eat first, Vigil suggested waiting an hour or two after your meal before exercising. That will allow the stomach to empty out.

Of course, that rule changes if you’ve overeaten.

“If you’re going to sit down to a Denny’s Grand Slam Breakfast, it’s going to be in your stomach for a lot longer,” said Leslie Bonci, a registered dietitian and owner of Active Eating Advice, a nutrition consulting company in Pittsburgh. “My general rule of thumb for my athletes is to wait an hour before exercising. And you want to keep the amount of food to about the size of your fist, not the size of a football.”

What is the best thing to eat before a workout?

Bonci suggested tailoring what you eat to the kind of exercise you’ll be performing. So, if you’re going to be running, drink about 20 ounces of liquid an hour beforehand, she said. And eat something small and carbohydrate-based, such as a granola bar, a banana or some dry cereal.

If you’ll be doing hot yoga, “you don’t want to start dehydrated,” Bonci said. “It’s not so energy expending as running, so you could do 8 ounces of juice and 12 ounces of water,” she said.

“If you’re going to be doing some degree of strength training — and that’s not just weight lifting, but also swimming since that’s got a strength component — it’s critical to have some protein. I’m not talking about a pound of bacon and a dozen eggs. The maximum should be 20 grams of protein. That could be 8 ounces of yogurt or 6 ounces of yogurt with some cereal on top of it.”

Swimmers, she said, should get a combination of protein and carbohydrates. “You might try a bagel thin or sandwich thin with two eggs and a little cheese,” she suggested. “It’s not a huge volume, but it provides some protein and carbohydrates.”

Those who will be biking “need to take the gut into account and think about what it’s going to feel like to be crouched over for a long time,” Bonci said. “You may not feel comfortable with an omelet in your stomach and even a six-inch sub may be pushing it.”

If you’re hoping to get a little extra fuel in the tank right before working out, or, say, between two halves of a soccer game, Vigil said it’s generally OK to boost your energy with a 100-200 calorie sports bar.