Intake
How to Gauge Your Fuel

By Dana Sullivan

A carbohydrate is a wonderful thing for athletes, but they're not all created equal. Though every gram stores four energy-boosting calories, how fast your body gets to burn them is another matter. "If you experience energy lapses during long workouts, experiment with your carbohydrate choices," says Kristin J. Reimers, associate director of the International Center for Sports Nutrition in Omaha, Nebraska. To do so, check out the glycemic index, which rates the speed at which carbohydrates are metabolized. Foods that rate high kick in after 20 minutes, while those below 50 provide sustained energy (white bread, with an index of 100, is the reference point).

If you plan to be out longer than one hour, prep by eating two grams of low-indexed food for each kilogram of body weight two hours before exercising. If you eat nearer your workout time, halve the helping. For a craving just before you start, try a high-index snack. Here's how some of our favorite carbo-rich foods stack up.

Baked goods
Bagel — 103
Bran muffin — 85
Oatmeal cookies — 79

Cereals
Corn flakes — 119
All-Bran — 60

Grains/Pasta
Instant rice — 128
Spaghetti — 59
Rye — 48
Barley — 36

Dairy
Ice cream — 87
Skim milk — 46
Yogurt — 20

Fruit
Banana — 76
Apple — 52
Grapefruit — 36
Plums — 34
Cherries — 32

Legumes
Chickpeas — 47
Lentils — 41

Vegetables/Nuts
Potato (baked) — 121
Peanuts — 21

Illustration by Tim Hussey