Dietary fat and body weight set point.

The level of body weight corresponding to the threshold where energy balance is spontaneously stable is influenced by factors contributing to variations in fat balance. In this regard, a high-fat diet is associated with an increase in ad libitum energy intake and can lead to an increase of several kilograms of body weight over a year. On a long-term basis, this spontaneous weight gain is expected to plateau because of the ability of fat gain to promote an increase in fat oxidation up to a level allowing the recovery of energy and fat balance. Recent evidence suggests that lipid-soluble organochlorine pollutants may also make energy and fat balance regulation more vulnerable in obese individuals by accentuating the decrease in plasma thyroid hormone concentrations, skeletal muscle oxidative enzymes, and resting metabolic rate induced by weight loss. These observations support the idea that the body weight set point may fluctuate according to the actual impact of factors influencing fat balance.