The introduction of low-fat, high-complex
carbohydrate diets far the prevention and treatment of
obesity was based on the causal link established between
dietary fat and body fatness. Observational and mechanistic studies show that because fat possesses a lower satiating power than
carbohydrate and
protein, a diet rich in fat can increase energy intake. The propensity to
gain weight is enhanced in susceptible persons, particularly sedentary people who have a
genetic predisposition to
obesity.
Low-fat diets cause
weight loss proportional to pretreatment
body weight in a dose dependent manner; that is,
weight loss is correlated positively to the reduction in
dietary fat content. A reduction of 10% fat energy produces an average 5-kg
weight loss in obese persons. As with traditional caloric counting diets, obese persons lose weight only if they adhere to the prescribed
low-fat diet. Failure to achieve a
weight loss and to maintain it may be attributed in part to lack of adherence to the diet. After a major
weight loss, an ad libitum
low-fat diet program appears to be superior to caloric counting in maintaining the
weight loss 2 years later. Replacing some fat with
protein instead of
carbohydrate may increase the
weight loss further. Moreover,
fat substitutes may make it easier to prevent and treat
obesity by making the diet palatable. More randomized, controlled, long-term dietary intervention studies are warranted to identify the optimal diet composition for the treatment of
obesity.