It is ironic that while millions of people are dying of starvation each year in most parts of the world, many Americans are dying as an indirect result of an overabundance of food. Further, billions of dollars are spent each year overfeeding the American public, which then leads to the spending of billions of dollars more each year on various weight loss methods. This review will investigate various aspects of overweight and obesity, and show how they are affected by physical activity. But first, we must define and differentiate between the terms overweight and obesity.

The terms overweight and obesity are often used interchangeably, but this is technically incorrect as they have different meanings. Overweight is defined as a body weight that exceeds the normal or standard weight for a particular person, based on his or her height and frame size. These standards are established solely on the basis of population averages. It is quite possible to be overweight according to these standard tables and yet have a body fat content that is average or even below average. For example, almost all college and professional football players are overweight by these tables, but few are overfat. There are also people who are within the normal range of body weights for their height and frame size by the standard tables, but who have, in fact, excessive body fat.