We all need energy to function and we get this energy from the foods we eat. The most efficient way for cells to harvest energy stored in food is through cellular respiration, a catabolic pathway for the production of adenosine triphosphate (ATP). ATP, a high energy molecule, is expended by working cells.
An Apple a Day. The calories in a McIntosh apple depend on its size. According to the U.S. Department of Agriculture, a medium-sized apple with its skin has about 95 calories. Eating an unpeeled apple is moderately higher in calories than a peeled apple, but don't rush to peel your apple.
Including foods that are low in fat and calories in your diet is a good way to satisfy hunger and control your weight. Eating foods high in fat and calories could result in weight gain, which increases your risk of several health problems. A large Gala apple contains about 116 calories and less than 1 g of fat.