[Obesity in the 21st century. Progress in etiopathogenesis and treatment]

Obesity is complex in its etiology and treatment. Its global incidence is increasing significantly. Favoring weight-loss can only bring beneficial effects. Obesity is a chronic condition with multifactorial origin. The discovery of the ob gene and its product, the OB protein or Leptin, neuropeptide Y, and the alterations of the metabolism of lipogenic tissues that inhibit appetite are significant advances in the understanding of its etiopathogenesis and treatment. This new knowledge will change the philosophy of the management of obesity. Obesity responds poorly to nonsurgical therapies. Its treatment must be long-term in spite of the considerable social and biological pressure that favor the regaining of weight. Treatment of the obese patient must be performed by a multidisciplinary team, and should include a hypoenergetic diet, exercise program, behavioral modifications, and in some instances, family therapy. The treatment of obesity should be tailored for each individual. Drug use in the treatment of obesity is not a substitute for modifying the individual's diet and physical activity. Bariatric surgery is indicated only when the BMI is greater than 30 kg/m2. Physicians and patients must interact closely and assess possible risks that are involved in its treatment against real benefits. A good relation between practitioner and patient is essential.