Obesity surgery: a model of programmed undernutrition.

Surgical treatment of obesity (bariatric surgery) is the only effective long term solution for many patients. The procedures are designed to produce reduced intake, various degrees of malabsorption of nutrients, or both. Micronutrient deficiencies, especially those involved in erythropoiesis and bone metabolism, are common to nearly all bariatric surgery. They are inconsistently responsive to supplementation. The pattern of deficiency associated with gastrointestinal bypass procedures suggests that absorption of micronutrients is more dependent upon the functioning of the gut as a whole than the capacity of any single segment.