Activate the gut–adipose Axis: Forsythia tea alleviates diet-induced obesity via gut microbiota–dependent Browning of white adipose tissue

This study investigated the mechanisms by which Forsythia tea (FT) alleviates diet-induced obesity via the gut-adipose axis. Following 8 weeks of high-fat diet (HFD) feeding to induce obesity in male C57BL/6 J mice, the HFD-fed mice were randomized into HFD and HFD + FT groups, with a normal diet (ND) group as control, for a subsequent 4-week intervention. The results demonstrated that FT significantly attenuated HFD-induced body weight gain and improved glucose tolerance and insulin sensitivity. Furthermore, FT effectively reversed dyslipidemia and suppressed systemic inflammation. Mechanistically, FT reshaped the gut microbiota, enhancing alpha diversity and enriching beneficial taxa. These microbial changes were associated with increased colonic short-chain fatty acid (SCFA) levels, particularly butyrate, and reinforced intestinal barrier integrity. Crucially, FT treatment markedly upregulated the expression of uncoupling protein 1 (UCP1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) in inguinal white adipose tissue (iWAT), indicating the activation of WAT browning. Correlation analyses strongly linked the enriched beneficial microbes to the improved metabolic phenotypes. In conclusion, our findings reveal that FT mitigates obesity and metabolic dysfunction by activating a microbiota-dependent gut-adipose axis that promotes WAT browning, supporting its potential as a functional beverage for obesity management. • Forsythia tea alleviates metabolic dysregulation and suppresses systemic inflammation. • Forsythia tea reduces fat accumulation, attenuates liver injury, and enhances short-chain fatty acid production. • Forsythia tea remodels the gut microbiota and promotes microbiota-dependent adipose browning. • Forsythia tea mitigates diet-induced obesity by activating the gut–adipose axis.