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.
Apparently the largest apple ever recorded was about 3lbs, which is about 1360g. Using that same page, that says that Americans eat on average 19.6 lbs of apples or 65 apples a year, that gives a mass of 136g per apple eaten by Americans on average. It really depends. A Mac book Pro weighs 2490 grams, while and Izod Classic only weighs 190 grams, both being Apples.