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Gastric bypass increases energy expenditure in rats


Bueter, M; Löwenstein, C; Olbers, T; Wang, M; Cluny, N L; Bloom, S R; Sharkey, K A; Lutz, T A; le Roux, C W (2010). Gastric bypass increases energy expenditure in rats. Gastroenterology, 138(5):1845-1853.e1.

Abstract

BACKGROUND: Mechanisms underlying weight loss maintenance after gastric bypass surgery are poorly understood. Our aim was to examine the effects of gastric bypass on energy expenditure in rats. METHODS: Thirty diet-induced obese male Wistar rats underwent either gastric bypass (n=14), sham operation ad libitum fed (n=8) or sham-operation body weight-matched (n=8). Energy expenditure was measured in an open circuit calorimetry system. RESULTS: Body weight after 70 days was lower after gastric bypass compared to sham ad libitum fed rats (p<0.0001). Sham-operated body weight-matched controls ate less than gastric bypass animals to reach the same weight (16.2+/-0.5g vs. 27.5+/-0.8g, p<0.001). Twenty-four hour energy expenditure was increased after gastric bypass (4.50+/-0.04 kcal/kg/h) compared to sham-operated ad libitum fed (4.29+/-0.08 kcal/kg/h) and sham-operated body weight-matched controls (3.98+/-0.10 kcal/kg/h, p<0.001). Gastric bypass rats showed higher energy expenditure during the light phase than both sham-operated control groups (sham ad lib: 3.63+/-0.04 kcal/kg/h vs. sham body weight-matched: 3.42+/-0.05 kcal/kg/h vs. bypass: 4.12+/-0.03 kcal/kg/h, p<0.001). Diet-induced thermogenesis was elevated after gastric bypass compared to sham-operated body weight-matched controls three hours after a test meal (0.41+/-1.9% vs. 10.5+/-2.0%, p<0.05). The small bowel of gastric bypass rats was 72.1% heavier due to hypertrophy compared with sham-operated ad libitum fed rats (p<0.0001). CONCLUSIONS: Gastric bypass surgery in rats prevented the expected decrease in energy expenditure subsequent to weight loss. Diet-induced thermogenesis was higher after gastric bypass compared to body weight-matched controls. Raised energy expenditure may be an additional mechanism explaining the physiological basis of weight loss after gastric bypass surgery.

BACKGROUND: Mechanisms underlying weight loss maintenance after gastric bypass surgery are poorly understood. Our aim was to examine the effects of gastric bypass on energy expenditure in rats. METHODS: Thirty diet-induced obese male Wistar rats underwent either gastric bypass (n=14), sham operation ad libitum fed (n=8) or sham-operation body weight-matched (n=8). Energy expenditure was measured in an open circuit calorimetry system. RESULTS: Body weight after 70 days was lower after gastric bypass compared to sham ad libitum fed rats (p<0.0001). Sham-operated body weight-matched controls ate less than gastric bypass animals to reach the same weight (16.2+/-0.5g vs. 27.5+/-0.8g, p<0.001). Twenty-four hour energy expenditure was increased after gastric bypass (4.50+/-0.04 kcal/kg/h) compared to sham-operated ad libitum fed (4.29+/-0.08 kcal/kg/h) and sham-operated body weight-matched controls (3.98+/-0.10 kcal/kg/h, p<0.001). Gastric bypass rats showed higher energy expenditure during the light phase than both sham-operated control groups (sham ad lib: 3.63+/-0.04 kcal/kg/h vs. sham body weight-matched: 3.42+/-0.05 kcal/kg/h vs. bypass: 4.12+/-0.03 kcal/kg/h, p<0.001). Diet-induced thermogenesis was elevated after gastric bypass compared to sham-operated body weight-matched controls three hours after a test meal (0.41+/-1.9% vs. 10.5+/-2.0%, p<0.05). The small bowel of gastric bypass rats was 72.1% heavier due to hypertrophy compared with sham-operated ad libitum fed rats (p<0.0001). CONCLUSIONS: Gastric bypass surgery in rats prevented the expected decrease in energy expenditure subsequent to weight loss. Diet-induced thermogenesis was higher after gastric bypass compared to body weight-matched controls. Raised energy expenditure may be an additional mechanism explaining the physiological basis of weight loss after gastric bypass surgery.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Institute of Veterinary Physiology
04 Faculty of Medicine > Center for Integrative Human Physiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:May 2010
Deposited On:14 Dec 2009 12:45
Last Modified:05 Apr 2016 13:37
Publisher:Elsevier
ISSN:0016-5085
Publisher DOI:10.1053/j.gastro.2009.11.012
PubMed ID:19931268
Permanent URL: http://doi.org/10.5167/uzh-25544

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