Weight loss in adult male Wistar rats by Roux-en-Y gastric bypass is primarily explained by caloric intake reduction and pre-surgery body weight

Am J Physiol Regul Integr Comp Physiol. 2024 Apr 8. doi: 10.1152/ajpregu.00169.2023. Online ahead of print.ABSTRACTDiets varying in macronutrient composition, energy density, and/or palatability may cause differences in outcome of bariatric surgery. In the present study, rats feeding a healthy low fat (LF) diet or an obesogenic high fat/sucrose diet (HF/S) were either subjected to Roux-en-Y gastric bypass surgery (RYGB) or sham surgery, and weight loss trajectories and various energy balance parameters were assessed. Before RYGB, rats eating a HF/S (n=14) diet increased body weight relative to rats eating a LF diet (n=20; p<0.01). After RYGB, absolute weight loss was larger in HF/S (n=6) relative to LF feeding (n=6) rats, and this was associated with reduced cumulative energy intake (EI; p<0.05) and increased locomotor activity (LA; p<0.05-0.001), finally leading to similar levels of reduced body fat content in HF/S and LF rats 3 weeks after surgery. Regression analysis revealed that variation in RYGB-induced body weight loss was best explained by models including a) post-surgery cumulative EI and pre-surgery body weight (R2=0.87) and b) post-surgery cumulative EI and diet (R2=0.79), each without significant contribution of LA. Particularly rats on the LF diet became transiently more hypothermic and circadianally arrhythmic following RYGB (i.e., indicators of surgery-associated malaise) than HF/S feeding rats. Our data suggest that relative to feeding a LF diet, cont...
Source: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology - Category: Physiology Authors: Source Type: research