The goals of nutritional care for athletes are simple and straightforward. For the most part, nutritional care should:

ensure that athletes are properly hydrated during periods of active training and competition.
provide adequate calories to meet growth and development needs, if in youth and adolescent years, and the extra needs of the physical activity
supply nutrients from food
instill sound nutrition principles and practices that will last a lifetime.
The best eating habits for the athlete may be as follows:

Design a meal pattern that fits your daily cycle. Plan to eat several times a day using regularly spaced meals and snacks to help meet caloric and nutrient needs.

Eat a diet rich in complex carbohydrates (starches). Starchy foods such as pasta, breads, cereals, potatoes, corn, peas and others provide a major energy source to fuel your activities. These foods are also a source of fiber, vitamins and minerals.

Drink sufficient fluids to stay hydrated during training and competition periods - don't wait until you are thirsty to drink.

Eat a diet that contains a variety of foods from breads and cereals; fruits; vegetables; meat and meat substitutes; and dairy foods. It is your best insurance for getting needed nutrients.
Diet and training work together:

Diet supplies the needed fuel sources and nutrients for physical activity.
Training improves the body's use of fuel and enhances muscle glycogen storage.
Pre-Game Rules

Eat lightly before an athletic competition.

Eat complex carbohydrates, keep protein and fat intakes low since these slow digestion.

Avoid bulky foods. They may stimulate bowel movements. Bulky foods include raw fruits and vegetables, dry beans and peas and popcorn.

Avoid gas-forming foods such as vegetables from the cabbage family and cooked dry beans.

Eat slowly and chew well.

Drink water to be adequately hydrated. One suggestion is to drink 2 cups of cool water 1-2 hours before the event. Follow this by drinking 1 to 2 cups of fluid 15 minutes before the event.

Avoid drastic changes in your normal diet routine immediately prior to competition. Some athletes prefer to use favorite foods which may give them a psychological edge.
Post-Game Rules

Consume carbohydrate-rich foods and beverages as soon as possible after competition. They will replenish glycogen stores quickly and get the athlete back into performance shape. Fruits, juices, high carbohydrate drinks and pop are examples.

Replace fluids that have been lost. For every pound that is lost, drink 2 cups of fluids.

Replace any potassium or sodium that has been lost during competition or training by using foods. Fruits and vegetables are excellent sources of potassium. Replace sodium by eating salty foods. If activity has exceeded 2 hours and is vigorous, a sports beverage will be helpful.

Return to your normal high carbohydrate diet at your next meal.