The body is supplied with energy when a person eats food. Energy from food in the form of fats, proteins and carbohydrates supports the many different functions of the body.Continue Reading
The body's energy requirements are normally measured in calories. In nutrition, the term "calorie" represents how much heat energy it takes to increase the temperature of 1 kilogram of water, which is around the same size as a quart, by 1 degree Celsius.
Two requirements are considered when calculating an individual's energy requirements: energy required for activity and basal metabolic requirements, or the heat lost from the body during rest at normal temperatures. On average, a person requires between 2,000 and 2,400 calories per day, but some people, such as large men who are very physically active, may require as many as 6,000 calories each day.
Fats provide the body with its most concentrated form of energy, supplying more than twice as much as carbohydrates or proteins at a given weight. For one gram of food, carbohydrates and proteins provide 4 calories and fats provide 9 calories. When a person eats foods that provide more energy than he needs, the body stores that energy in the form of fat. This can result in weight gain. On the other hand, if a person does not consume enough energy, the body uses stored fat as an energy source and weight loss can occur.Learn more about Biology