Women who have bariatric surgery need to reduce the amount of fat they eat after surgery to reap the full benefit of the procedure and protect their liver function, according to researchers from the University of Michigan Medical School, Ann Arbor, MI, the College of Veterinary Medicine, Cornell University, Ithaca, NY and the University of Colorado-Anschutz Medical Campus, Aurora, CO.
Nearly 80% of patients that receive bariatric surgery are women, yet mechanistic pre-clinical studies have focused on males. The goal of this study was to determine the metabolic impact of diet- and surgery-induced weight loss in males, females and ovariectomised female mice.
For the study, ‘Diet-Dependent Sex Differences in the Response to Vertical Sleeve Gastrectomy,’ published ahead of print in the American Journal of Physiology-Endocrinology and Metabolism, researchers studied a mouse model of vertical sleeve gastrectomy. Male and female mice were fed a 60% high-fat (HFD) diet before undergoing either vertical sleeve gastrectomy (VSG) or sham surgery. Mice either remained on HFD or were switched to a standard chow diet post-surgically. When maintained on HFD, both males and females decreased fat mass and improved oral glucose tolerance after VSG.
After dietary intervention, additional adiposity was lost in both surgical groups. Ovariectomised females had a blunted decrease in fat mass on a HFD, but lost significant adiposity after dietary intervention. In addition, energy expenditure was only impacted by dietary but not surgical intervention across all groups. Males decreased hepatic triglyceride levels after VSG, which was further decreased after dietary intervention. Intact and ovariectomised females had a blunted decrease in hepatic triglycerides after surgical intervention but a significant decrease after dietary intervention.
Interestingly, the more pronounced effect of surgery on hepatic lipids in males was strongly associated with changes in expression of hepatic microRNAs and genes that have previously been linked to hepatic lipid regulation and systemic energy homeostasis.
"These data suggest that maintaining females on a [high-fat diet] diminishes the impact of surgery on reducing hepatic triglycerides," the researchers cautioned. The findings "highlight the importance of considering the additive impact of dietary intervention on surgical outcome" in light of the sex differences associated with weight loss surgery, explained Dr Darleen Sandoval of the University of Colorado-Anschutz Medical Campus, and corresponding author of the study.
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