If you're a runner, you might turn a critical eye to your diet as a way to improve your times. And you should -- what you eat can impact not only how fast you run, but also how you feel before, during and after exercise. Sports nutrition is more complicated than simply piling on the carbohydrates before a race. Eating right can improve your time if you look not just at carb intake, but also proteins, fats and vitamins and minerals.
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Carbohydrates should dominate a runner's diet, supplying 60 to 70 percent of your daily calories, recommends the American Academy of Orthopaedic Surgeons. However, your optimal amounts of daily carbohydrate might not be the same as another runner's. The Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine recommend between 2.7 and 4.5 grams of carbohydrate per pound of body weight daily, which equals between 405 and 675 grams per day. Carbohydrate foods with a low-glycemic index, such as complex carbohydrates, increase endurance more effectively than high-glycemic index foods, such as simple sugars, because they keep your blood sugar stable. Fruits, vegetables, legumes and whole-grains generally have a low-glycemic index.
Getting Enough Protein
Runners need protein on a daily basis to rebuild damaged tissue. As with carbohydrate, your weight and the distance you run weekly will affect your need for protein. While the protein recommendation for the average American is 0.36 grams per pound of body weight, the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine recommend runners get 0.5 to 0.8 grams per pound. Without adequate protein, your muscle tissue may break down, which will affect your speed.
Fueling with Fats
Although you might shy away from it, fat is nothing to be scared of, as long as you eat the right amounts and the right types. Your body needs fats for energy and to metabolize the fat-soluble vitamins A, D, E and K. The Academy of Nutrition and Dietetics, Dietitians of Canada, and American College of Sports Medicine recommends that between 20 to 35 percent of your daily calories come from fats, including 10 percent from saturated fat, 10 percent from polyunsaturated fat and 10 percent from monounsaturated fat.
Vitamins and Minerals for Runners
Vitamin and mineral deficiencies can slow you down. In a study published in the June 2005 "Journal of the American Dietetic Association," 36 percent of female athletes and 6 percent of males had iron deficiency, which can cause fatigue and shortness of breath. Blood loss during menstruation increases the risk of iron deficiency in women. In addition to iron, found in meats and some plant foods, such as dark green leafy vegetables, you need calcium and vitamin D to maintain bone density and B vitamins to ensure energy production and muscle repair. Antioxidants such as vitamins C and E, minerals, such as selenium, and carotenoids, such as beta carotene, help protect cells from damage. Five or more servings per day of fruits and vegetables, along with nuts, seeds and whole-grains can ensure your intake of essential vitamins and minerals.