Obesity develops when energy intake exceeds energy expenditure.
The etiology of obesity is multifactorial. The first federal guidelines on identifying, evaluating, and treating overweight and obesity in adults were recently released. There are no good long-term studies of dietary fat intake and weight gain and few studies of weight loss following reductions in dietary fat. If the impact of a low fat diet is to reduce the chances of overeating, such a modest effect would be expected. It is clear that a low fat diet would have an important role in maintaining a weight loss.