title: Decreased energy density and changes in food selection following Roux-en-Y gastric bypass.
abstract: OBJECTIVE
  The main objective was to test the hypothesis that dietary energy density (DED) decreases after Roux-en-Y gastric bypass (gastric bypass).
  
  
  METHODS
  A total of 43 patients (31 women and 12 men) aged 43 (s.d. 10) years, with body mass index (BMI) 44.3 kg/m(2) (4.9), were assessed preoperatively at 6 weeks and 1 and 2 years after gastric bypass. Self-reported energy intake (EI), food weight (FW) and food choice were assessed using a dietary questionnaire. DED was calculated by dividing EI by FW (kcal/g). Number of dropouts was 4 of 203 visits.
  
  
  RESULTS
  Percent weight loss (%WL) was 13.5% at 6 weeks, 30.7% at 1 year and 31.8% at 2 years post surgery (P<0.001 for all). EI decreased from 2990 to 1774, 2131 and 2425 kcal after 6 weeks and 1 and 2 years postoperatively, respectively (P<0.001 at all time points). FW changed from 2844 to 1870 g/day at 6 weeks (P<0.001) and 2416 g/day after 1 year (P<0.05), but was not significantly different from baseline 2 years postoperatively (2602 g/day, P=0.105). DED decreased from 1.07 to 0.78 kcal/g at 6 weeks (P<0.001) and 0.90 kcal/g (P<0.001) and 0.96 kcal/g (P=0.001) after 1 and 2 years, respectively. All statistical comparisons were made from baseline. There was no correlation between changes in DED and %WL, neither after 1 year (r=-0.215; P=0.183) nor after 2 years (r=-0.046; P=0.775) post surgery.
  
  
  CONCLUSIONS
  Besides substantial reduction in EI and large variation in FW, patients reported decreased DED over 2 years following gastric bypass. Despite lack of association between the reduction in DED and percentage weight loss, changes in food choice were overall nutritionally beneficial.
authors.affiliation: Department of Gastrosurgical Research and Education, Sahlgrenska Academy, Gothenburg, Sweden. anna.laurenius@vgregion.se
authors.forename: A
authors.initials: A
authors.lastname: Laurenius
authors.forename: I
authors.initials: I
authors.lastname: Larsson
authors.forename: K J
authors.initials: KJ
authors.lastname: Melanson
authors.forename: A K
authors.initials: AK
authors.lastname: Lindroos
authors.forename: H
authors.initials: H
authors.lastname: Lönroth
authors.forename: I
authors.initials: I
authors.lastname: Bosaeus
authors.forename: T
authors.initials: T
authors.lastname: Olbers
mesh_terms: D000328:Adult; D015992:Body Mass Index; D004032:Diet; D002149:Energy Intake; D005247:Feeding Behavior; D005260:Female; D005518:Food Preferences; D015390:Gastric Bypass; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery*; D010352:Patient Dropouts; D057566:Self Report; D011795:Surveys and Questionnaires; D015431:Weight Loss