Abstract: A discussion of obesity proposes that weight is physiologically regulated and dieting cannot alter this biological fact. This point is confirmed by the fact that most dieters lose weight only temporarily. Physical activity is the most effective method for decreasing the body's demand for fat. The concept that fatness is a major cause of disease is challenged. The rise in average weight since 1960 has accompanied a decrease in the death rate from cardiovascular disease. Exceptions are diabetes and high blood pressure. Weight control through exercise can be an important treatment. Most motivation to lose weight is based on looking better rather than feeling better. The body's "set point" (normal weight) for fatness is detailed. This point is reinforced by referenced scientific studies. Popular diets and diet books are described. Studies are cited to show that exercise uses calories and also regulates appetite; it is suggested that this lowers the "set point" and is more advantageous than a reducing diet. organizations for fat people are listed. changes in attitudes toward fatness is advocated since most weight reduction regimens are ultimately unsuccessful.