The influence of obesity and its treatment on the immune system.

Obesity and weight reduction are significant public health concerns in the United States and other developed countries. Although much research has examined the adverse health consequences of overweight and the benefits of weight loss, the effects on immunologic function of either excess adiposity or weight reduction treatments for obesity have received relatively little attention. In general, studies of immunologic function in obese humans and experimental animals indicate that excess adiposity is associated with impairments in host defense mechanisms. Definitive studies of immune function in human obesity are, however, still needed. Preliminary investigations suggest that certain types of weight reduction strategies produce further alterations in immune responsiveness. More research is needed to confirm or refute these initial findings and to assess the long term consequences of weight loss for overweight individuals. Nutritional and neuroendocrine status are among the factors likely to be involved in modulation of immune responses in obesity and as a consequence of dieting and weight reduction.