The most efficient sources of food energy are carbohydrates. Plants, grains, milk, fruits, and honey all provide this nutrient. Carbohydrates are composed of the chemical compounds of simple and complex sugars. These compounds are glucose, fructose, sucrose, maltose, starch, and glycogen. All of these forms of sugar can be converted within the body according to supplies and demands. Basically, however, all sugars must be converted to glucose for use by the muscles and other tissues. Sugar is stored in the body in the form of glycogen. When the glycogen storage areas in the liver and muscles are filled, the excess amounts of glucose are converted into fats and stored in limited quantities in the fat cells throughout the body.
An average, well-nourished person must replenish carbohydrates supplies throughout the day because the readily available supply of glucose will usually be depleted by only a half-day of sedentary activities without replenishment. For an active, athletic person, the supply would last for a shorter time. Fifty-five to sixty percent of daily food intake should be in the form of carbohydrates, and, as Smith (1976) has stated, it should be well over 50 percent for active athletes.
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