The Truth About Calories. What is a calorie? A calorie is considered  in scientific terms one unit of energy. This energy is used to walk,  talk, breath, sleep, stretch or run. All activities burn calories. The  human body exerts its energy by using calories it receives from food.  Thus when we speak of calories we associate the term with dieting and  weight loss.
In general terms, foods contain calories. We may see them described  in other terms such as a carbohydrate, a fat and a protein. These terms  are measured in units called grams. So the basic building block of each  gram is a defined number of calories.
1 gram of carbohydrates contain four (4) calories h 
1 gram of protein contains four (4) calories 
1 gram of fat contains nine (9) calories 
While you eat, food is broken down inside of your stomach and  metabolized into your blood stream. It is either used and burned up  efficiently through activity or stored in our cells and fat cells are  created. A total of 3,500 stored calories equal one (1) pound of body  fat. Tus, in order to lose that one-pound of fat, we have to burn up  3,500 calories per exercise to remove it. It sounds a little easier than  it looks on paper.
Your body will need to a certain amount of calories in order to  maintain itself properly. The act of breathing, walking, running,  sleeping and talking all burn a certain amount of calories. This rate is  called the Basal Metabolism Rate or (BMR) as it is known. It is  calculated differently for both men and women. When your body is at rest  it does not burn as many calories as when it is exercising
Physical activities such as jogging, walking, and skiing also help burn  calories. The more physical exercise you get, the more calories you will  burn. Thus you are keeping your body in shape by eating right and  working off the excess calories through exercise. Thus, exercise in  general helps to keep your metabolism rate higher and continues to burn  fat long after the exercising is done. It will also help your body burn  excess fat efficiently at rest.
If you are looking to start losing some of those extra pounds, remember  each pound is 3,500 calories that you must burn in order to lose one  pound of fat. You will want to first consult a physician as with  starting any new diet or exercise program.