Readers often ask about eating before and after exercise: Carbo-load before? Protein-pack after? How many calories do I burn running out on a dinner check?

First, let's clear the fog: Much of what's published on this topic is aimed at competitive athletes and endurance exercisers. If you do four to six moderate-intensity, half-hour sessions a week -- and aren't trying to add a lot of muscle -- you don't need to worry much. Just follow the usual healthy-human advice: Eat a varied diet that centers of fresh produce and lean protein; eat regular small meals for a constant supply of life fuel; and go easy on the crap.

In Depth About the Crew | Ask the Crew Susan Morse Health section assistant editor, hiker, kayaker, swimmer and dabbler in a variety of exercise regimens. » VISIT THE ARCHIVES Browse the Archives Recent Columns Discussion Transcripts Save & Share Tag This Article  Saving options 1. Save to description:  Headline (required) 2. Save to notes (255 character max):  Blurb 3. Tag This Article

In fact, most folks can even work out in the morning without eating breakfast. Whether they enjoy it is another question.

Energy for physical activity comes from glycogen stores in the muscles. Because glycogen stays in your muscles basically until you need it, you don't need to fuel up right before working out, says Katherine A. Beals, an associate professor in the Division of Nutrition and Department of Family Practice and Preventive Medicine at the University of Utah.

Glycogen comes from carbohydrates; most meals should include 50 percent carbs (make a lot of them veggies and whole grains), 20 percent protein and 30 percent fat. You needn't worry about depleting muscle glycogen unless you are exercising strenuously for 45 minutes or more.

So why might you want to eat something before exercise? Carbs also raise blood glucose levels, which help fuel your brain, Beals explains. Drops in blood glucose can cause lack of concentration, dizziness, fatigue and headaches.

Nancy Clark, a registered dietitian, American College of Sports Medicine fellow and author of a sports nutrition guidebook, agrees.

"If your brain isn't fed, it says, 'This isn't fun,' and your motivation goes down," Clark says. "People think, 'If I don't eat [before working out] I'll burn fat and lose weight,' but it doesn't work that way. Losing weight is determined by your calories-in/calories-out equation at the end of the day." As we say often, to safely lose weight you want to run a daily deficit of 200 to 300 calories.

To ensure adequate brainpower during a workout, both experts suggest a pre-session healthy carb-based snack totaling around 300 calories, like a half a bagel or some yogurt and a banana. (Early morning exercisers who simply cannot stomach food so soon before exercise should eat a snack close to bedtime the night before, Clark says.)

For higher-intensity or long-duration exercise, research shows that carbohydrate consumption soon before -- and even during -- enhances performance.

After exercise -- particularly intense workouts and strength training -- some protein is beneficial, Clark and Beals say, because it breaks down into amino acids, which are used to repair and build on muscle fibers torn during exercise. Include carbs in this meal to help restore muscle glycogen.

"It doesn't really matter" how soon after a session the average exerciser eats, Beals says, because "they have likely not depleted their glycogen stores to any significant degree." Studies show that over a 24-hour period, the timing of eating has very little to do with the total amount of glycogen stored.

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