Advances in understanding the role of gut microbiota in fat deposition and lipid metabolism

Abstract The gut microbiota has emerged as a pivotal regulator of host lipid metabolism and energy homeostasis. A growing body of evidence reveals that variations in the composition and metabolic activity of intestinal microbes are closely associated with differences in adipose tissue deposition across species. Notably, increased abundance of Firmicutes and a reduced proportion of Bacteroidetes and butyrate-producing bacteria have been linked to enhanced fat accumulation. Key microbial metabolites such as short-chain fatty acids (SCFAs) influence lipid metabolism through multiple pathways, including the activation of GPR41/43 receptors, modulation of the bile acid–FXR/TGR5 axis, and regulation of hepatic lipogenesis. Additionally, the gut–brain axis plays a critical role in controlling feeding behavior via neuroendocrine signaling. This review summarizes current advances in understanding the roles of dominant bacterial phyla and beneficial genera—including Clostridium butyricum and Faecalibacterium prausnitzii —in fat metabolism. We further explore the mechanisms by which gut microbiota modulate lipid synthesis and catabolism through SCFA production, bile acid signaling, and AMPK/PPAR-related pathways. These insights highlight the potential of microbiota-targeted strategies to restore lipid metabolic balance, offering novel opportunities for applications in health management, nutritional interventions, and microbial therapeutics. Graphical Abstract