Aerobic metabolism is a way for your cells to convert fat, carbohydrate and sometimes protein into energy, but only in the presence of oxygen. Aerobic metabolism is slow, so it is useful for sustained activities like jogging or dancing rather than short bursts of effort like sprinting or weightlifting.
Aerobic metabolism converts fat and carbohydrate into units of cellular energy called ATP. Aerobic metabolism is very efficient, producing 34 molecules of ATP from every molecule of glucose, compared to the two ATP molecules anaerobic metabolism generates. Aerobic metabolism is also the only means by which your cells can use fat for fuel, which is part of the reason why aerobic activities like swimming or cycling are such an effective means to lose weight.
Your body performs aerobic metabolism all day long to provide energy for activities of daily living. Because aerobic metabolism requires water and oxygen, it is the reason that humans breathe constantly and part of the reason why you need to drink water. Carbohydrates are a necessary ingredient for aerobic metabolism – even to burn fat. Because the muscles and liver can only store a limited amount of carbohydrate between meals, aerobic metabolism is also the reason why you need to eat carbohydrates every day. Although your body can metabolize protein for energy in the absence of carbohydrates, it is a slow and inefficient process. Aerobic metabolism in the absence of carbohydrate can only keep up with activities with a very low energy cost, leaving you feeling sluggish.