Polycystic ovary syndrome (PCOS) is a prevalent reproductive, endocrine, and metabolic disease that affects 5–18% of women worldwide, with a rising incidence. Hyperandrogenemia and insulin resistance are two key pathophysiological factors that contribute to PCOS, both of which contribute to a variety of health issues such as menstrual irregularities, obesity, dysfunctional glucose and lipid homeostasis, infertility, mental disorders, and cardiovascular and cerebrovascular diseases. Despite ongoing studies, the origin and pathogenesis of PCOS remain elusive; there is also a clinical need for simpler, more effective, longer lasting, and more comprehensive treatments for women with PCOS. The gut–fat axis, a critical regulatory route for metabolism, endocrine function, and immune response, has received considerable interest in recent years in the research of the etiology and treatment of metabolic illnesses such as type 2 diabetes mellitus and non-alcoholic fatty liver disease. The latest research in PCOS has revealed significant alterations in the homogeneity and phylogenetic diversity of the gut microbiota. Animal research using fecal microbiota transplantation has confirmed the importance of gut microbiota in regulating insulin sensitivity and sex hormone balance in PCOS. Furthermore, studies have shown a decrease in the volume and/or activity of brown adipose tissue (BAT) in PCOS patients, a change that alters adipokine release, leading to insulin resistance and hyperandrogenemia, aggravating PCOS progression. Given the function of BAT in increasing energy expenditure and alleviating metabolic parameters, efforts to activate BAT or induce browning of white adipose tissue have emerged as possible treatments for PCOS. Recent research has suggested that the gut microbiota can influence BAT creation and activity via metabolites such as short-chain fatty acids and bile acids, as well as the gut–brain axis. Cold exposure, healthy dieting, metformin, bariatric surgery, glucagon-like peptide 1 receptor agonists and melatonin have all been shown in basic and clinical studies to modulate BAT activity by influencing the gut microbiota, demonstrating significant clinical potential. However, more studies into the regulation mechanisms of the gut–BAT axis are required to produce more effective, comfortable, and safe tailored therapeutics for PCOS.
