Special to CNN.com
When you eat and what you eat can affect your performance and the way you feel during your workout. Coordinate your meals, snacks and fluids to make the most of your exercise routine.Eating before exercise can slow you down
When you exercise after a large meal, you can feel sluggish or have an upset stomach, cramping and diarrhea. That's because your muscles and your digestive system are competing with each other for resources.
"Your body can digest food while you're active, but not as well as it can when you're not exercising," notes Stephen DeBoer, a registered dietitian at Mayo Clinic, Rochester, Minn. This is partly because your body is trying to do two things requiring blood supply and energy at once — digesting the food you eat and providing fuel to keep your muscles moving.Time it right: Before, during and after your workout
On the flip side, not eating before you exercise can be just as bad as eating too much. Low blood sugar levels that result from not eating can make you feel weak, faint or tired, and your mental abilities may be affected as well, making you slower to react. So what can you do?
To get the most from your workout, follow these guidelines:
- Eat a full breakfast. Wake up early enough to eat a full breakfast. "Most of the energy you got from dinner last night is used up by morning," says DeBoer. "Your blood sugar is low. If you don't eat, you may feel sluggish or lightheaded while exercising." If you plan to exercise within an hour after breakfast, eat a smaller breakfast or drink something to raise your blood sugar, such as a sports drink.
- Time your meals. Eat large meals at least three to four hours before exercising. If you're having a small meal, eat two to three hours before exercising.
Most people can eat snacks right before and during exercise. The key is how you feel. Some people feel lightheaded during the first 10 to 15 minutes of their workout if they eat within an hour before exercise. Do what works best for you.
- Don't skip meals. Skipping meals may cause low blood sugar, which can make you feel weak and lightheaded.
If you're short on time before your workout, and your choice is candy or nothing, eat the candy because it can improve your performance, compared with eating nothing. But keep in mind, all candy is high in sugar and low on nutrients, so a snack of yogurt and a banana would be a better choice.
- Eat after your workout. To help your muscles recover and to replace their glycogen stores, eat a meal that contains both protein and carbohydrates within two hours of your exercise session if possible.
Food provides your body with necessary energy. To make the most of your workouts, focus on:
Carbohydrates: Your body's chief source of fuel
You'll feel better when you exercise if you eat foods high in carbohydrates and low in fat. Your body stores excess carbohydrates as glycogen — primarily in your muscles and liver. Your muscles rely on stored glycogen for energy.
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. High-fiber foods may give you gas or cause cramping. Fructose, a simple sugar found in fruit, can increase the tendency for diarrhea with high-intensity exercise.
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.
A diet containing at least 40 percent to 50 percent of calories from 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 and fats: Important, but not your body's top fuel choice
Protein isn't your body's food of choice for fueling exercise, but it does play a role in muscle repair and growth. Most people can easily get the protein they need from such foods as poultry, meat, dairy products 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. Try to get most of your fat from unsaturated sources such as nuts, fatty fish or vegetable oils. Avoid fatty foods just before exercising, though. Fats sit in your stomach longer, causing you to feel less comfortable.
Water: Drink plenty to avoid dehydration
Your body uses water to carry nutrients such as sugar (glucose) to cells and to remove waste products from the cells. The presence of water in your body ensures that you can safely sustain physical activity. As you exercise, your body produces heat. This heat leaves your body as you perspire, taking with it electrolytes — elements, such as potassium, calcium, sodium and chlorine. If you don't replace the fluid you lose during exercise, your heart rate increases and your temperature rises, putting you at risk of dehydration as well as compromising your workout.
To stay well hydrated during exercise, the American College of Sports Medicine recommends that you drink eight glasses of water every day and more on days when the temperature and humidity are high.
Drink at least one glass of water before and after your workout and every 10 to 15 minutes during your workout to replace fluid lost in perspiration. Avoid substituting water with coffee, tea or soda, because they contain caffeine, which acts as a diuretic, a substance that causes your body to lose even more water.
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 also helps you rehydrate more quickly, notes DeBoer.
Signs and symptoms of inadequate hydration may include:
- Loss of coordination
- Mental confusion
- Dry skin
- Elevated body temperature
- Diminished urine output
When it comes to eating and exercise, everyone is different. So pay attention to how you feel during your workout and your overall performance. Let your experience guide you on which pre- and post-exercise eating habits work best for you.
December 22, 2004