Longitudinal assessment of food intake, fecal energy loss, and energy expenditure after roux-en-y gastric bypass surgery in high-fat-fed obese rats

Andrew C. Shin, Huiyuan Zheng, R. Leigh Townsend, Laurel M. Patterson, Gregory Holmes, Hans Rudolf Berthoud

Research output: Contribution to journalArticle

29 Scopus citations


Background: The efficacy of Roux-en-Y gastric bypass (RYGB) surgery to produce weight loss has been well-documented, but few studies have measured the key components of energy balance, food intake, and energy expenditure longitudinally. Methods: Male Sprague-Dawley rats on a high-fat diet underwent either RYGB, sham operation, or pair feeding and were compared to chow-fed lean controls. Body weight and composition, food intake and preference, energy expenditure, fecal output, and gastric emptying were monitored before and up to 4 months after intervention. Results: Despite the recovery of initially decreased food intake to levels slightly higher than before surgery and comparable to sham-operated rats after about 1 month, RYGB rats maintained a lower level of body weight and fat mass for 4 months that was not different from chow-fed age-matched controls. Energy expenditure corrected for lean body mass at 1 and 4 months after RYGB was not different from presurgical levels and from all other groups. Fecal energy loss was significantly increased at 6 and 16 weeks after RYGB compared to sham operation, and there was a progressive decrease in fat preference after RYGB. Conclusions: In this rat model of RYGB, sustained weight loss is achieved by a combination of initial hypophagia and sustained increases in fecal energy loss, without change in energy expenditure per lean mass. A shift away from high-fat towards low-fat/high-carbohydrate food preference occurring in parallel suggests long-term adaptive mechanisms related to fat absorption.

Original languageEnglish (US)
Pages (from-to)531-540
Number of pages10
JournalObesity Surgery
Issue number4
StatePublished - Apr 1 2013


All Science Journal Classification (ASJC) codes

  • Surgery
  • Endocrinology, Diabetes and Metabolism
  • Nutrition and Dietetics

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