title: Body composition and energy expenditure after weight loss following bariatric surgery.
abstract: OBJECTIVE
  To assess the effectiveness of biliopancreatic diversion (BPD) in the treatment of morbid obesity and to evaluate how the procedure affects body weight.
  
  
  METHODS
  Fourteen morbidly obese subjects studied before and 30 months after BPD and fifteen healthy volunteers matched for age, sex and height (controls).
  
  
  METHODS
  Comparison of the following parameters were made in the study groups before surgery and 30 months after BPD and with those of the controls group: fat mass, fat-free mass, non-protein substrate oxidation, basal metabolic rate, plasma glucose, insulin and free fatty acid concentrations.
  
  
  RESULTS
  Obese subjects lost 60.38+/-10.71 kg of weight during 18 months following surgery and then remained stable for another 12 months, when this study was performed. Weight loss was substantially due to a loss of fat mass (FM: 60.13+/-13.01 kg before and 19.02+/-8.61 kg after BPD; p<0.001). FM were not statistically different between post-obese subjects and controls; however, post-obese patients retained significantly more fat free mass (FFM) than controls. Subsequently, basal metabolic rates of post-obese subjects were higher than those of the control group (p<0.05). Fasting non-protein respiratory quotient (npRQ) was significantly lower before BPD than 30 months after the surgery (0.798+/-0.04 vs. 0.90+/-0.048, p<0.001), suggesting that, while obese, patients oxidized more lipids than carbohydrates. Moreover, fasting and two-hour plasma glucose and insulin concentrations decreased significantly after BPD to values comparable to those of the control group.
  
  
  CONCLUSIONS
  Weight loss in obese patients after BPD is mainly due to lipid malabsorption, but increased energy expenditure associated with retaining a high FFM in physically active post-obese subjects may also play a role, enabling them to maintain long-term reduced body weights.
authors.affiliation: Cattedra di Medicina Interna II, CNR Centro di Fisiopatologia dello Shock, Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Benedetti
authors.forename: G
authors.initials: G
authors.lastname: Mingrone
authors.forename: S
authors.initials: S
authors.lastname: Marcoccia
authors.forename: M
authors.initials: M
authors.lastname: Benedetti
authors.forename: A
authors.initials: A
authors.lastname: Giancaterini
authors.forename: A V
authors.initials: AV
authors.lastname: Greco
authors.forename: M
authors.initials: M
authors.lastname: Castagneto
authors.forename: G
authors.initials: G
authors.lastname: Gasbarrini
mesh_terms: D000328:Adult; D001481:Basal Metabolism; D015904:Biliopancreatic Diversion; D001786:Blood Glucose / Q000032:analysis; D001823:Body Composition; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery*; D015431:Weight Loss
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin