Calorie as Energy Unit

Calories are not nutrients either; a calorie is just a unit of measurement, like a foot or an inch in British unit, and m or kg in international units. Calorie listings indicate the potential energy value of foods or food components. Protein and carbohydrate each contain 4 calories per gram; fat contains 9 calories per gram. (Thus, you would consume more than twice as many calories in a teaspoon of butter as in a teaspoon of sugar). Vitamins, mineral, and water contain no calorie; neither does fiber, since it is indigestible to human beings.

Energy expenditure, the amount of energy your body needs in order to carry out an activity or bodily process, is also expressed in calories. For example, an average sized apple contains about 100 calories. A twenty-minute walk will burn up just about as many calories. (However, it will take one to one and a half hour to walk-off a wedge of apple pie).

How many calories do you need per day? This depends on your physical activity and other factors. This subject will be covered more thoroughly later.