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.
The U.S. Department of Agriculture nutrient database lists the caloric content of apples -- unspecified type -- based on size. The calorie count ranges from 77 calories contained in a small fruit to 116 calories in a large. The Washington State Apple Coalition states that a large 8-ounce generic apple contains 130 calories. A medium-sized Honeycrisp apple will fall somewhere in this range. Other Benefits