You weren't fooled, though. You've always known carbs are your muscles' best fuel and without enough, your 5k race would be more like a three-mile death march. But not all carbs are created equal. Some will give you a boost of energy while others can wipe you out. What's best? Read on to learn how to make carbs work for you.
Body's Best Fuel
Of the three major nutrients your body uses for energy--carbohydrates, fat and protein --carbs are the most easily accessible form of fuel. During digestion, carbs are broken down into glucose (the most basic sugar molecule), quickly absorbed into the bloodstream (protein and fat molecules take longer to convert to blood sugar) and picked up by your body's other cells to metabolize into energy. Glucose that isn't used immediately is turned into glycogen and stored in the muscles for the short-term, or converted to body fat for the longer-term.
Carbs are commonly categorized as "simple" or "complex". Made of a single sugar molecule or two linked together, simple carbohydrates include lactose (milk sugar), fructose (fruit sugar) and sucrose (table sugar). Complex carbohydrates such as starch and fiber in grains and other plants are long strings of sugar molecules.
Years ago, some people claimed simple carbs were bad and complex carbs were good. But in reality, it's far more complicated. Whether or not a carbohydrate food has much health value has more to do with the nutrients it contains and the amount of processing it has undergone, than with the length of its sugar chain.
Potato chips or fresh mango? Not hard to guess mango is the better carb for your health. Both supply energy for your muscles and brain, but only the mango is packed with disease-fighting, energy-sustaining nutrition. Most of your carbohydrates should come from unprocessed or minimally processed fruits, vegetables and whole grains; low-fat and skim milk; and legumes such as peas, beans and lentils.
Each athlete is different, but generally "women athletes should consume 55 to 70 percent of their calories from carbohydrates," says sports nutritionist Tara Gidus, spokesperson for the American Dietetic Association. An endurance athlete, who needs plenty of carbs to burn, should be at the higher end of the range, whereas an athlete whose focus is on weight training should eat toward the lower amount. If your diet is 2,000 or so calories, aim for about 275 to 350 grams per day of carbs, depending on your level of cardiovascular activity. For 2,600 calories, your carb intake might span 355 to 455 grams.
If you're not sure if you're eating the right amount, registered dietitian Nancy Clark, author of Nancy Clark's Food Guide for Marathoners: Tips for Everyday Champions, suggests eyeballing your plate. Two-thirds should be covered with healthy carbs, she says. Or go further and log your daily food choices into an online journal that calculates your intake of carbohydrates, fats, vitamins and more.Fruits and Vegetables
What really bugged nutritionists during the low-carb years was that people were eating less of the healthiest foods of all--fruits and veggies. Bad idea.
A recent report issued jointly by the World Cancer Research Fund and the American Institute for Cancer Research suggests that diets with five to 10 servings of fruits and vegetables daily could prevent at least 20 percent of all cancers. Other research indicates that every one serving increase per day of fruits and veggies is associated with a four percent lower risk of coronary heart disease. Higher intakes of fruits and veggies are also linked to greater bone density.