Exocarpium Citri Grandis alleviates postmenopausal obesity in ovariectomized mice through gut microbiota remodeling and metabolic reprogramming

Exocarpium Citri Grandis (ECG, Huajuhong), the epicarp of Citrus grandis ‘Tomentosa’, traditionally used to resolve phlegm, is also applied against phlegm-dampness-type obesity. Further evidence is needed to clarify its anti-obesity effects and role in gut microbiota modulation. In this study, ECG significantly reduced body weight, serum TG, TC, and LDL-c, while HDL-c increased (p < 0.05). Metabolic cage, qPCR, and Western blot analyses of ingWAT, pgWAT, and iBAT showed increased energy expenditure, upregulated thermogenic genes (e.g., Ucp1, Atp2a2), downregulated lipid synthesis genes (e.g., Acc, Fas), and enhanced lipolytic and mitochondrial gene expression (e.g., Atgl, Mgll).It also showed strong anti-inflammatory effects by reducing TNF-α, IL-6, and IL-1β, increasing mucus layer thickness, and upregulating intestinal barrier genes (Zo-1, Occludin).16S rDNA sequencing revealed increased β-diversity, SCFA-producing bacteria, and elevated lactic and hexanoic acid levels. ECG may reduce postmenopausal obesity by remodeling gut microbiota and reprogramming metabolism, indicating its potential as a functional food.