Rational diet construction for obesity requires understanding of two facts: (1) energy expenditure must be considered along with diet and (2) psychological incentive must be maintained. Ironically, time may prove that diet construction in the present day sense will play a minor role in obesity correction. It has become progressively more apparent that psychological and behavioral characteristics of the individual represent the true etiological factors in obesity. Correction of these depends on successful behavior modification of the individual. The best current concept is that diet and exercise are fundamental for obesity control, but also that behavior modification is the underlying essential for long-term regulation. Physiologically and psychologically, mild and grand obesity are different. In mild obesity the problem is usually one of insidious, often slight shift of caloric balance to one beyond weight maintenance over a prolonged period. Dietary intake and energy expenditure are both usually involved in the change