CD obese-prone rats, but not obese-resistant, robustly ferment resistant starch without increased weight or fat accretion

OBJECTIVE: We used CD obese prone (OP) and obese resistant (OR) rats to examine how weight gain and fat accretion relate to fermentation levels and microbiota composition after feeding resistant starch (RS). METHODS: After feeding OP rats and OR rats a high fat (HF) diet for 4 weeks, rats were stratified into three groups: fed either a HF diet (HF), switched to a low fat (LF) diet or a LF diet supplemented with RS (LF-RS, 20% wt) for 4 weeks. Energy intake, body weight, fermentation variables and microbiota composition were determined. RESULTS: In OP rats, RS elicited robust fermentation (increased cecal contents, short chain fatty acids and serum GLP-1). Total bacteria, species of the Bacteroidales family S24-7 and the archaea Methanobrevibacter smithii increased. The robust fermentation did not elicit higher weight or fat accretion compared to control rats fed the same isocaloric diets (HFLF±RS). In OR rats, body weight and fat accretion were also not different between HFLF±RS diets, but RS elicited minimal changes in fermentation and microbiota composition. CONCLUSIONS: Robust fermentation did not contribute to greater weight. Fermentation levels and changes in microbiota composition in response to dietary RS differ by obese phenotype.