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Unfortunately, what counts as the right stuff often depends on the situation. Your body can’t do everything at once. Restricting your calorie intake to promote weight and fat loss can make it very difficult to build muscle mass or train for endurance events. If you’re trying to combine any or all of these goals, things can get pretty complicated.
This article will help you understand the role that carbohydrates play in fueling exercise and recovery and how both the timing and nutritional makeup of your meals and snacks can help you achieve your performance goals.
With all the emphasis placed on exercising to lose weight, many people are surprised to hear that exercise itself doesn’t actually burn much fat as fuel. Exercise uses up the calories you've eaten, but most "fat burning" occurs when your body then has to turn to fat stores to fuel basic bodily functions.
To fuel moderate and high intensity exercise, your body relies primarily on carbohydrates (glucose), which are broken down quickly to fuel muscle cells. (Your body can't turn fats and proteins into usable energy quickly enough to meet the demands of exercising muscles.)
Therefore, higher intensity cardio and strength training activities will burn more glucose as fuel, and more calories overall. Learn more about the myth of the "fat burning zone" by reading this Ask the Expert Q & A .
Action Step: Don’t limit your carbohydrates. Most people need about 100-150 grams (400-600 calories) of carbohydrates every day just to fuel their brains and central nervous systems. On top of that, you need additional carbs to replace the energy stores you used when exercising. If you’re trying to lose weight, research shows that a diet where 55-60% of total calories come from carbohydrate is ideal for most physically active people.
It takes time to digest your food and turn it into glycogen, which is the primary fuel your muscle cells actually use during exercise. Glycogen is made out of glucose (which comes from carbohydrates) and is stored in both your muscle cells and liver. As long as you're eating enough nutrients to meet your activity needs, your body can store enough glycogen to handle about 2000 calories worth of high-intensity activity or 4000 calories worth of lower-intensity activity—even if you haven’t eaten in a while.