BARIATRIC ORIGINAL ARTICLE Changes in eating behaviour and meal pattern following Roux-en-Y gastric bypass A Laurenius 1 , I Larsson 2 , M Bueter 3 , KJ Melanson 4 , I Bosaeus 5 , H Berte ´us Forslund 5 , H Lo ¨nroth 1 , L Fa ¨ndriks 1 and T Olbers 1,6 1 Department of Gastrosurgical Research and Education, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; 2 The Obesity Unit, Department of Body Composition and Metabolism, Sahlgrenska University Hospital, Gothenburg, Sweden; 3 Division of Visceral and Transplantation Surgery, Department of Surgery, University Hospital, Zu¨rich, Switzerland; 4 Energy Balance Laboratory, Department of Nutrition and Food Sciences, University of Rhode Island, Kingston, RI, USA; 5 Department of Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden and 6 Department of Investigative Medicine, Imperial Weight Centre, Imperial College London, London, UK Background: Little is known about eating behaviour and meal pattern subsequent to Roux-en-Y gastric bypass (RYGB), knowledge important for the nutritional care process. The objective of the study was to obtain basic information of how meal size, eating rate, meal frequency and eating behaviour change upon the RYGB surgery. Materials and methods: Voluntary chosen meal size and eating rate were measured in a longitudinal, within subject, cohort study of 43 patients, 31 women and 12 men, age 42.6 (s.d. 9.7) years, body mass index (BMI) 44.5 (4.9) kg m À2 . Thirty-one non-obese subjects, 37.8 (13.6) years, BMI 23.7 (2.7) kg m À2 served as a reference group. All subjects completed a meal pattern questionnaire and the Three-Factor Eating Questionnaire (TFEQ-R21). Results: Six weeks postoperatively meal size was 42% of the preoperative meal size, (Po0.001). After 1 and 2 years, meal size increased but was still lower than preoperative size 57% (Po0.001) and 66% (Po0.001), respectively. Mean meal duration was constant before and after surgery. Mean eating rate measured as amount consumed food per minute was 45% of preoperative eating rate 6 weeks postoperatively (Po0.001). After 1 and 2 years, eating rate increased to 65% (Po0.001) and 72% (Po0.001), respectively, of preoperative rate. Number of meals per day increased from 4.9 (95% confidence interval, 4.4,5.4) preoperatively to 6 weeks: 5.2 (4.9,5.6), (not significant), 1 year 5.8 (5.5,6.1), (P ¼ 0.003), and 2 years 5.4 (5.1,5.7), (not significant). Emotional and uncontrolled eating were significantly decreased postoperatively, (both Po0.001 at all-time points), while cognitive restraint was only transiently increased 6 weeks postoperatively (P ¼ 0.011). Conclusions: Subsequent to RYGB, patients display markedly changed eating behaviour and meal patterns, which may lead to sustained weight loss. International Journal of Obesity (2012) 36, 348 – 355; doi:10.1038/ijo.2011.217; published online 29 November 2011 Keywords: Roux-en-Y gastric bypass; meal size; eating rate; meal pattern; eating behaviour; TFEQ-R21 Introduction Currently, the most successful long-term treatment for morbid obesity is obesity surgery including procedures such as Roux- en-Y gastric bypass (RYGB). 1 These operations successfully achieve and maintain long-term weight loss and improve mortality, morbidity and quality of life. 2–4 Until recently, the success of RYGB was commonly attributed to mechanical constraint through gastric volume reduction and calorie malabsorption secondary to the bypass of small intestine. 5 However, in patients, gastric pouch sizes do not correspond with weight loss or regain after gastric bypass. 6 The degree of malabsorption subsequent to RYGB is still controversial, although Odstrcil et al. 7 recently demonstrated a minor reduction in energy absorption after RYGB with a Roux-limb length of 150 cm and a biliopancreatic limb from 40 to 75 cm beyond the ligament of Treitz. Other mechanisms contribut- ing to postoperative weight loss may include reduced hunger and/or increased satiation, 8 increased energy expenditure 9 and altered taste perception, 10 all of which may be mediated by alterations in gastrointestinal and central neuroendocrine signalling. 8 – 11 The Roux limb could also be an important determinant for regulating food intake after RYGB surgery 12 Received 10 May 2011; revised 22 September 2011; accepted 29 September 2011; published online 29 November 2011 Correspondence: A Laurenius, Department of Gastrosurgical Research and Education, Sahlgrenska Academy, University of Gothenburg, Bruna stra ˚ket 20, Sahlgrenska University Hospital, S-413 45 Gothenburg, Sweden. E-mail: anna.laurenius@vgregion.se International Journal of Obesity (2012) 36, 348–355 & 2012 Macmillan Publishers Limited All rights reserved 0307-0565/12 www.nature.com/ijo