Eat Before A Workout: Is It Necessary?

Honestly, when working out first thing in the morning, do I really need to eat before? Especially if I'm just doing a quick 30-minute run or elliptical?

-- Alicia, 26, Shreveport, Louisiana
With all of the marketing of sports drinks, bars, gels and powders, this is an excellent question to ask. There's certainly no harm in eating -- and it might help you meet your fitness goals by giving you more energy during the actual run or elliptical workout.

"It's a contradiction, but you really do need the calories to perform well," Barbara Lewin, R.D., L.D., a sports nutritionist who works with professional and Olympic athletes, said in an earlier interview about sports drink alternatives. "The calories are what's enabling you to work out at your best. If you're not well-fueled, you're not going to work out as hard."

And certainly, if you're planning an endurance training session, you must eat. According to Andrea Hacker Thompson, M.S., R.D., of the American College of Sports Medicine, endurance athletes should eat even when they aren't hungry. She wrote:

A race car never starts a race without new tires and a full tank of gas, so an endurance athlete should not start a workout without fueling. Eating before a workout guarantees that the body starts with a full tank of glycogen.

But even for those of us who aren't trying to run an ultramarathon, if we plan a rigorous session of 90 minutes or longer, getting a bit to eat beforehand is a good idea. To understand why, it's important to know how our bodies use energy during a workout. When we exert ourselves, we burn glycogen -- the cache of glucose we keep stored in our muscle and liver cells. After we've gone through that store of carbohydrates, we can start to feel fatigued. As Thompson explains for the ACSM, the body can store about 2,000 calories in glycogen. If you plan to go over that amount (and, wow, that's quite a workout if you do!), you could begin to get light-headed, weak or just plain exhausted.

But for a 30 minute treadmill session? You probably don't have to make a concerted effort to eat enough. You do, on the other hand, have to keep hydrated. Water is fine for a half-hour run, but any workout over an hour may require some electrolyte replacement -- such as a sports drink or a piece of fruit.

Beyond the question of whether or not to eat, there are other considerations. It's important not to eat too much -- or too little. And to know when to eat it. The Mayo Clinic provides a guideline, suggesting a small snack about an hour before exercising or a medium meal two hours before a gym session. For a full meal, they recommend giving yourself a three to four hour time period between eating and hitting the gym. Overdo it, and you could give yourself stomach cramps or even diarrhea.

Most of all, it's important to note your own reaction to food and figure out an eating plan that's right for you. Feel fine during a morning run, even without that yogurt? Skip it. But if you need a little something for extra energy, there's nothing wrong with starting with a snack.