title: Effects of RYGB on energy expenditure, appetite and glycaemic control: a randomized controlled clinical trial.
abstract: OBJECTIVE
  Increased energy expenditure (EE) has been proposed as an important mechanism for weight loss following Roux-en-Y gastric bypass (RYGB). However, this has never been investigated in a controlled setting independent of changes in energy balance. Similarly, only few studies have investigated the effect of RYGB on glycaemic control per se. Here, we investigated the effect of RYGB on EE, appetite, glycaemic control and specific signalling molecules compared with a control group in comparable negative energy balance.
  
  
  METHODS
  Obese normal glucose-tolerant participants were randomized to receive RYGB after 8 (n=14) or 12 weeks (n=14). The protocol included a visit at week 0 and three visits (weeks 7, 11 and 78) where 24-h EE, appetite and blood parameters were assessed. Participants followed a low-calorie diet from weeks 0-11, with those operated at week 12 serving as a control group for those operated at week 8.
  
  
  RESULTS
  Compared with controls, RYGB-operated participants had lower body composition-adjusted 24-h EE and basal EE 3 weeks postoperatively (both P<0.05) but EE parameters at week 78 were not different from preoperative values (week 7). Surgery changed the postprandial response of glucagon-like peptide-1 (GLP-1), peptide YY3-36 (PYY), ghrelin, cholecystokinin, fibroblast growth factor-19 and bile acids (all P<0.05). Particularly, increases in GLP-1, PYY and decreases in ghrelin were associated with decreased appetite. None of HOMA-IR (homeostasis model assessment-estimated insulin resistance), Matsuda index, the insulinogenic index, the disposition index and fasting hepatic insulin clearance were different between the groups, but RYGB operated had lower fasting glucose (P<0.05) and the postprandial glucose profile was shifted to the left (P<0.01).
  
  
  CONCLUSIONS
  Our data do not support that EE is increased after RYGB. More likely, RYGB promotes weight loss by reducing appetite, partly mediated by changes in gastrointestinal hormone secretion. Furthermore, we found that the early changes in glycaemic control after RYGB is to a large extent mediated by caloric restriction.
authors: Department of Nutrition, Exercise and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors: J B
authors: JB
authors: Schmidt
authors: Department of Nutrition, Exercise and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark.|C-ENDO Endocrinology Clinic, Calgary, AB, Canada.
authors: S D
authors: SD
authors: Pedersen
authors: Department of Nutrition, Exercise and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark.|Novo Nordisk A/S, Bagsværd, Denmark.
authors: N T
authors: NT
authors: Gregersen
authors: Department of Nutrition, Exercise and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors: L
authors: L
authors: Vestergaard
authors: Department of Nutrition, Exercise and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors: M S
authors: MS
authors: Nielsen
authors: Department of Nutrition, Exercise and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors: C
authors: C
authors: Ritz
authors: Department of Endocrinology, Hvidovre University Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: S
authors: S
authors: Madsbad
authors: Department of Endocrinology, Hvidovre University Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: D
authors: D
authors: Worm
authors: Department of Endocrinology, Hvidovre University Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: D L
authors: DL
authors: Hansen
authors: Novo Nordisk A/S, Bagsværd, Denmark.
authors: T R
authors: TR
authors: Clausen
authors: Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors: J F
authors: JF
authors: Rehfeld
authors: Department of Nutrition, Exercise and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors: A
authors: A
authors: Astrup
authors: NNF Center for Basic Metabolic Research and Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: J J
authors: JJ
authors: Holst
authors: Department of Nutrition, Exercise and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors: A
authors: A
authors: Sjödin
mesh_terms: D000328:Adult; D001066:Appetite / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D003718:Denmark / Q000453:epidemiology; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass; D054439:Ghrelin / Q000378:metabolism*; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D009767:Obesity, Morbid / Q000453:epidemiology / Q000378:metabolism / Q000601:surgery*; D019518:Postprandial Period; D016896:Treatment Outcome; D015431:Weight Loss
chemical_list: D001786:Blood Glucose; D054439:Ghrelin