Obesity: new aspects

Obesity is the consequence of how the body regulates energy intake, energy expenditure and energy storage. Evolutionary mechanisms have rendered mammals capable of surviving scarcity of nutrients. The present abundance of food has led to an epidemic of obesity in the developed and in the developing world. Adipose tissue has long been considered an inactive reserve depot of fat but it appears to be an active tissue, directly and actively involved in the control of body weight and energy balance via the secretion of a large number of molecules with regulatory potential (adipokines), explaining the biological mechanisms of the relationship between an excess of body fat and metabolic disturbances, diabetes mellitus, and cardiovascular disease. There is also a relationship between obesity and cancer. Sex steroids are involved in the sexually dimorphic pattern of fat distribution. Testosterone induces a visceral fat depot. Paradoxically, a decline in testosterone, such as that observed with aging, leads to an accumulation of fat in the visceral depot favorably responding to normalization of plasma testosterone. Treatment of obesity is disappointing. The present cornerstones, caloric restriction and exercise, are rarely maintained in the longer-term. Pharmacological treatment is modestly helpful. It is probably public education and the production of healthier food by the industry that might be successful. The latter might be spurred by the costs of obesity-related disease to the health care system.