Caloric Intake

Caloric intake is defined as the amount of heat energy the body receives from eating food. The unit used to measure this amount of energy is called the calorie. It is also used to measure how much energy the body expends during human activity or inactivity such as running, walking, sitting, thinking, or sleeping.

The calorie is the metric unit of measurement for energy. Specifically called the food calorie (sometimes the nutritional or dietary calorie) within the food industry, it is equivalent to the kilogram calorie, or kilocalorie (symbolized as kcal). The kilocalorie is defined as the amount of heat energy needed to increase the temperature of one kilogram of water by one degree within the Celsius temperature scale. (As a note of clarity, outside the food industry the gram calorie, or the small calorie, is also referred to as the calorie and is defined as the amount of heat energy necessary to increase the temperature of one gram of water by 1° Celsius.) Thus, one food calorie is equal to one kilogram calorie, which is equal to 1,000 gram calories.

The intake of food calories is an important part of how well any person maintains a healthy lifestyle. Food calories are especially important in how effectively an athlete trains and ultimately competes. Eating a balanced diet is a key part to sports nutrition. The correct combination of fuel (calories ingested), especially from carbohydrates, proteins, and fats, gives a person plenty of energy for top performance whether it is running, walking, sitting, thinking, or sleeping.

Carbohydrates are a very important source of caloric intake for the human body. They come in the form of such foods as fruits, vegetables, pastas, breads, cereals, rice, and honey. For a balanced diet, proper health, and peak performance, they should provide about 60-70% of a person's daily caloric intake. Carbohydrates provide energy when the body changes the starches and sugars within carbohydrates into glycogen, which is then stored in the liver and muscles. Glycogen is easily converted into glucose in order to provide endurance and strength for short-duration/high-intensity sports activities and exercises. A person's performance level will drop rapidly if the body eliminates its supply of carbohydrates and it is forced instead to intake proteins and fats for energy, which are less efficient fuels (calories) for the body. For maximum performance in such activities and exercises, a person should eat plenty of carbohydrates several days before the sporting event so that the body will possess plenty of glycogen within the muscles. During the event, if the competition lasts for more than an hour, the athlete should replace lost carbohydrates with additional ones. For instance, many bicyclists love to eat spaghetti before a long race because it is filled with carbohydrates. They then fill up with sports energy bars and drinks containing carbohydrates throughout the day of competition.

Proteins should consist of from about 12% to 15% of a person's daily caloric intake. They come in various foods such as beans, dairy products, eggs, and nuts. Proteins provide the human body with power to build new tissues and generate other essential functions. They are not stored in the body but are turned immediately into energy or changed into fat. Physically active people need more proteins then inactive people. Endurance athletes such as body builders often consume plenty of proteins as a way to produce fuel to build strong muscles. However, it is a falsehood that by eating plenty of protein and/or taking protein supplements a person can become a muscular person. Building muscles depends on heredity, the intensity of the workout, the amount of training, and getting sufficient calories in a daily diet. The average diet of a United States citizen contains sufficient proteins for regular muscle building. Thus, if a person does not eat enough carbohydrates, then proteins are consumed rather than allowed to perform their regular function of building new tissues. When a body has enough carbohydrates, then proteins produce about 5% of energy. If not enough carbohydrates are available, then proteins can produce up to 10% of energy. The caloric intake of fats are needed only in small amounts. They come as saturated fats in such foods as cheese, eggs, meats, and milk, and as unsaturated fats in such foods as canola oil, corn oil, and palm oil. Fats are used as the energy source primarily when a person is inactive or during low to medium rates of exercise. When carbohydrates are used up, however, fats are burned instead, which decreases the performance level of an athlete because energy is produced less efficiently.

For adults and for children over the age of two years, the American Heart Association (AHA) provides general dietary recommendations in order to maintain a normal weight-to-height ratio and to provide an adequate caloric intake of food. The AHA suggests that a diet should consist primarily of whole grains, beans, fruits and vegetables, low-fat and nonfat dairy products, fish, and lean meats. The diet should also consist of low caloric intakes of saturated fats, trans fatty acids (trans fats), partially hydrogenated oils, cholesterol, and supplemental sugar and salt.

Caloric intake is important. The caloric intake of healthy foods is even more important to the health and well-being of all persons.

SEE ALSO Calories; Carbohydrates; Fat intake; Protein ingestion and recovery from exercise.