Eating for Exercise
1. Food Before Exercise
- Most importantly, be sure you're well hydrated before exercise. Exercise performance suffers with as little as 2 percent loss of body weight due to dehydration. Drink at least 2 cups of water about 2 hours before exercise. Drink another 2 cups of water within 20 minutes of exercise.
- Don't exercise when the body is depleted of nutrients (like before breakfast). Note that performing aerobic exercise on an empty stomach or when you're hungry does not increase the amount of fat you burn; rather, it may cause protein to be sacrificed as fuel.
- For optimum exercise performance, be sure to consume a healthy, well-balanced diet all through the day! (For more information on healthy food choices, click here.)
- Don't exercise immediately after eating, because the body shifts fluid away from muscles and into the gastrointestinal tract during digestion. The ideal time for fitness activities is about ...
- 1/2 hour after a light snack.
- 1 hour after a light meal, heavy snack, or meal replacement drink.
- 2 hours after a regular meal.
- 3 hours after a Thanksgiving-type feast.
- Consuming sweets (such as honey, candy, or soda) immediately before exercise does not provide a quick burst of energy, but may cause a rise in insulin followed by a drop in blood sugar resulting in fatigue.
2. Food During Exercise
- Most importantly, be sure to drink plenty of water during exercise. Drinking water during exercise does not cause upset stomach or cramps; whereas restricting water during exercise may cause severe dehydration and limit performance. Be aware that exercise blunts the sense of thirst. "If you wait until you notice your thirst, you're already becoming dehydrated." So whether you feel thirsty or not, drink 1/2 cup of water every 10-15 minutes. Ideally, exercisers should consume adequate fluids during activity so that body weight remains relatively unchanged before and after exercise.
- Note that muscle cramps are not caused by inadequate salt intake, but by excess water loss through perspiration. Salt tablets will aggravate dehydration by drawing fluids into the stomach. Prevent muscle cramps during exercise by keeping well hydrated.
- For people who exercise up to an hour in moderate environmental conditions, the most appropriate fluid to drink is cool water. The typical American diet provides ample electrolytes (sodium, potassium, chloride, and magnesium) to replace what is lost by sweat. However, persons who exercise strenuously for more than an hour or exercise in extreme environmental conditions (neither of which is recommended!) may require a sports beverage containing carbohydrates and electrolytes.
- Don't consume food during exercise, because the body shifts fluid away from muscles and into the gastrointestinal tract for digestion.
3. Food After Exercise
- Most importantly, drink more water! If you don't believe you lose much water during exercise, weigh yourself immediately before and after exercise. The difference is water loss. Ideally, exercisers should consume adequate fluids during activity so that body weight remains relatively unchanged before and after exercise.
- Sorry, if you lost weight during exercise, the loss is not due to burning fat but to losing water. Consume 2 cups of water for every pound of body weight lost during exercise.
- Note that muscle cramps are not caused by inadequate salt intake but by excess water loss through perspiration. Salt tablets will aggravate dehydration by drawing fluids into the stomach. Prevent muscle cramps after exercise (especially the night after exercise) by keeping well hydrated.
- Don't consume a heavy meal in the first hour after exercise.
- Do enjoy a snack or light meal about 30 minutes after exercise. The ideal post-exercise snack is light and nutritious, containing mainly carbohydrates and protein in a ratio of about 2:1. Examples:
- 1 cup of fruit juice with protein powder.
- 1 cup of 1 percent milk, fat-free ice cream, or nonfat yogurt.
- 1 apple with 1 inch cube of low-fat cheese.
- 2 slices of whole wheat bread with 2 thin slices of turkey, optional mustard.
- To achieve the best results from exercise, be sure to consume a healthy, well-balanced diet all through the day!
Reprinted with permission from HIV Fitness Guidelines. References are available online.