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    The human body is like a machine. It needs fuel to do work. Nutrients are fuel for the body. They are chemical substances in foods that the body needs for growth and energy. The body uses nutrients to carry out life process. There are five kinds of nutrients - carbohydrates, fats, proteins, vitamins, and minerals. Some foods are rich in one nutrient. Most foods contain many nutrients.

    A balanced diet is especially important to athletes. Athletic activities are hard work. An athletes body burn fuel rapidly. It requires a greater supply of fuel than does a person who is not an athlete. Eating health foods increases an athlete's power and endurance. Healthful eating helps an athlete manage the weight and protect him from injuries.

    Most nutrition experts say that an athlete's diet should be high in carbohydrates. Carbohydrates are nutrients that supply the body with energy. They also help build muscle. Starches such as bread and pasta are carbohydrates. They fuel the body with energy over a long period of time. Sixty to 70 to percent of the food an athlete eats should be high in carbohydrates.

    Water is also important to athletes. More than two-thirds of the human body is made up of water. People lose some of that liquid when they sweat. Athletes must replace the lost fluid. Drinking a liter of water before each competition helps maintain the necessary water balance.

   Regardless of the sport, every athlete should eat a meal three or four hours before competing. Fueling the body on carbohydrates, such as cereal, bread, and pasta, is important. The meal should include fruits and vegetables too. They supply the body with important minerals and additional carbohydrates.

    Athletes should avoid sugary foods, such as candy and soft drinks. Although they can give a quick energy "boost"; these foods also cause a subsequent energy "drop". Most importantly, an athletes should drink two or three cups of caffeine-free fluids. A balanced pre-game meal helps an athlete reach peak performance.

The following are the functions of nutrients for the human body, except ____.