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Whether you're a recreational athlete or a marathon runner, what you eat and when you eat it can affect your performance and the way you feel while you're exercising.
You'll feel better when you exercise if you eat foods high in carbohydrates and low in fat. That's true whether you're a marathon runner or a walk-the-office-stairwell person. Carbohydrates keep your blood sugar normal and fuel your muscles during exercise. "Your body gets used to using whatever you feed it," says DeBoer. "The more carbohydrates you eat, the more efficiently your body uses carbohydrates." Cereals, breads, vegetables, pasta, rice and fruit are good carbohydrate sources. But right before an intense workout, avoid carbohydrates high in fiber, such as beans and lentils, bran cereals, and fruit. The fructose in fruit can increase the tendency to have diarrhea with hard exercise, and high-fiber foods may give you gas or cause cramping. If you don't like to eat solid foods before exercising, drink your carbohydrates in sports beverages or fruit juices. "Research shows it makes no difference in performance whether you drink your carbohydrates or eat them," says DeBoer. Do what feels comfortable to you. When you exercise intensely for more than an hour, you'll need to consume additional carbohydrates or you'll start to lose energy. Sip a sports drink or chew on a sports bar high in carbohydrates. If you're exercising at any pace for 1 hour or less, these probably won't make a difference. Low-carbohydrate diets - those in which fewer than 25 percent of calories come from carbohydrates - impair your body's ability to replace glycogen, your muscles' fuel. A diet containing at least 40 percent to 50 percent carbohydrates allows your body to store glycogen, but if you're a long-distance runner or you exercise for long periods of time, you might want to consume more carbohydrates regularly and consider carbohydrate loading before a big athletic event.
Protein isn't your body's food of choice for fueling exercise, but it does play a role in muscle repair and growth. If you exercise three times a week, a diet containing 0.5 to 0.75 grams of protein per pound of body weight is sufficient. If you're a competitive athlete, up your intake to 0.6 to 0.9 grams per pound of body weight. Most people can easily get the protein they need from such foods as poultry, meat, dairy foods and nuts and don't need additional protein supplements. Fat is an important, although smaller, part of your diet. Fats, along with carbohydrates, provide fuel for your muscles during exercise. A good rule of thumb is to multiply your desired weight by 0.45, and the result is the number of fat grams to consume in a day. Try to get most of your fat from sources such as nuts, fatty fish or olive oil. Avoid fatty foods just before exercising, though. Fats sit in your stomach longer, causing you to feel less comfortable.
To stay well hydrated, drink six to eight glasses of fluids daily, plus consume at least 4 to 10 additional ounces of water for every 15 minutes of exercise. Electrolytes - elements such as potassium, sodium and chlorine - are depleted when you sweat. If you don't replace the fluid you lose during exercise, your heart rate increases and your temperature rises, putting you at risk of heat illness as well as compromising your workout.If you're a competitive athlete, weigh yourself before and after you exercise. For every pound you've lost, DeBoer recommends drinking up to 24 ounces of fluid.Water is generally the best way to replace lost fluid, unless you're exercising for more than 60 minutes. In that case, sip a sports drink to help maintain your electrolyte balance and give you a bit more energy from the carbohydrates in it. The sodium in sports drinks helps you rehydrate more quickly, notes DeBoer.