The Mechanism of Weight Loss after Ileo-gastrostomy for Morbid Obesity

Twelve patients (weight 107-178 kg and age range 19-43 years) were investigated following ileo-gastrostomy for morbid obesity. A number of variables were studied prospectively, pre- and postoperatively, to determine the cause of weight loss-previously attributed to malabsorption or decreased caloric intake. Weight loss of 10.9-36.5 kg, mean 22.9 kg, occurred. Three-day calorie counts demonstrated a postoperative decrease in daily caloric consumption of 320-3870, mean 1975 cal. Analysis of body compartment composition after derivation of lean body mass (from calculation of total body water with tritiated water) showed a mean decrease in adipose tissue of 17.7 kg. Postoperative weight loss, mainly fat, could not all be accounted for by decreased caloric consumption or steatorrhea (72-h stool fat increased by a mean of 30 g). Pulmonary studies showed no significant change in respiratory quotient, but a large decrease in both postoperative utilization of oxygen and the production of carbon dioxide. This may indicate an alternate, anaerobic, energy cycle utilization. Other statistically significant variables included a large fall in cholesterol, LDH cholesterol and triglycerides, and smaller decrease in HDL cholesterol. Changes in gastro-intestinal (GI) hormones and cell counts in stomach and small intestine were also measured and will be reported later.