title: Does reduction in gastric acid secretion in bariatric surgery increase diet-induced thermogenesis?
abstract: BACKGROUND
  Patients who have undergone gastrectomy for benign ulcer do not develop obesity. Furthermore, morbidly obese patients who undergo biliopancreatic diversion (BPD), Roux-en-Y gastric bypass (RYGBP) and vertical banded gastroplasty (VBG) plus truncal vagotomy, may lose more weight compared with patients who undergo VBG alone. A common characteristic of the above is the reduction of gastric hydrochloric acid secretion. We investigated whether reduction in gastric acid increases dietary-induced thermogenesis because of maldigestion of foods, and this may account for the greater weight loss in the above situations.
  
  
  METHODS
  22 volunteers without symptoms from the upper gastrointestinal tract were studied. Gastric pH was measured and resting energy expenditure (MREE), using indirect calorimetry, was determined before and 8 hours after consumption of a standard meal. Parameters were measured again after 2 months administration of proton pump inhibitors in all volunteers.
  
  
  RESULTS
  Although significant reduction of gastric acid secretion occurred (p < 0.01), following administration of proton pump inhibitors, the fasting and postprandial MREE remained unchanged (p > 0.05).
  
  
  CONCLUSIONS
  The reduction in gastric acid secretion does not increase the energy requirements for digestion of foods and thus is neither the mechanism responsible for the increased weight loss observed after RYGBP or BPD, nor the explanation for the lean appearance of gastrectomized patients.
authors.affiliation: Department of Surgical Oncology, Heraklion University Hospital, University of Crete Medical School, Greece. melissas@med.uoc.gr
authors.forename: John
authors.initials: J
authors.lastname: Melissas
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Kampitakis
authors.forename: George
authors.initials: G
authors.lastname: Schoretsanitis
authors.forename: John
authors.initials: J
authors.lastname: Mouzas
authors.forename: Elias
authors.initials: E
authors.lastname: Kouroumalis
authors.forename: Demetrios D
authors.initials: DD
authors.lastname: Tsiftsis
mesh_terms: D000328:Adult; D000713:Anastomosis, Roux-en-Y; D002151:Calorimetry; D004032:Diet; D004063:Digestion / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D005743:Gastrectomy; D005744:Gastric Acid / Q000378:metabolism*; D015390:Gastric Bypass; D015391:Gastroplasty; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000503:physiopathology* / Q000601:surgery*; D022722:Thermogenesis / Q000502:physiology*; D015431:Weight Loss / Q000502:physiology*