Race-Day Mistake Number 4

Your fitness watch says you're burning 800 calories an hour, so you cram down food.

Trail Mix

Trail Mix     Photo: Cary Bass/Flickr

Problem: Balancing your caloric budget doesn't work during exercise. "You can't replace everything you lose while you're performing," says Born. "But the body has tens of thousands of calories in fat stores."

Solution: In efforts longer than an hour, two-thirds of your energy comes from body fat. Supplement with 240-280 calories per hour.

From Outside Magazine, Sep 2011 Get the Latest Issue

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