Composite dietary fiber alleviates obesity-induced skeletal muscle atrophy by regulating gut microbiota-derived short-chain fatty acids in mice.

Obesity-induced muscle atrophy is a major health issue, in which gut microbiota play a key role in regulating metabolism and muscle health. This study investigated how composite dietary fiber protects against muscle atrophy in mice fed a high-fat diet (HFD). After 24 weeks of obesity induction, mice were divided into two groups: one continued on the HFD, while the other received the HFD supplemented with composite dietary fiber for 8 weeks. Composite dietary fiber ameliorated HFD-induced metabolic dysregulation by reducing adipose accumulation and improving insulin resistance. Notably, composite dietary fiber preserved skeletal muscle mass and function and downregulated the expression of key proteolytic markers Atrogin-1 and MuRF-1. The intervention enriched beneficial gut microbiota, particularly Bifidobacterium and other short-chain fatty acid (SCFA)-producing taxa, and elevated SCFA levels in both the colon and serum, with butyric acid increasing by 123.8% and 19.4%, respectively. PICRUSt2 analysis demonstrated enhanced microbial pyruvate and butanoate metabolism pathways, and correlation analyses revealed close relationships among microbiota, SCFAs, and muscle parameters. Collectively, these data suggest a potential mechanism whereby composite dietary fiber counteracts muscle atrophy in obesity by modulating the gut microbiota to increase SCFA production and downregulate proteolytic signaling, implicating its potential as a dietary intervention for muscle metabolic disorders.