Contribution of bariatric surgery to the comprehension of morbid obesity.

Convinced that morbid obesity was not due to food excess but rather to a metabolic disorder, we searched in the literature for data in favor of a metabolic disorder. We have found evidence in support of the thesis that the cause of morbid obesity is the inability to burn excessive caloric intake normally. It would involve the difficulty to increase heat with the amount of calories taken, which would be faulty and force fat deposition. This mechanism called dietinduced thermogenesis (DIT) allows the dispersion by heat of excessive calories to obtain energy balance. Results from bariatric surgery and particularly biliopancreatic diversion (BPD) give further support to this thesis. BPD would improve heat production to a meal (DIT) by one of these mechanisms: increased insulin sensitivity, change in intestinal hormone secretion, or chronic lipid malabsorption. Available results show that surgery, to be efficient, must change the physiology and not solely decrease food intake.