Adipocyte Browning: A Promising Avenue in Anti-Obesity Therapy

Adipocyte browning refers to the inducible transdifferentiation or de novo recruitment of thermogenically active beige adipocytes within white adipose tissue depots. Beige adipocytes, characterized by multilocular lipid droplets and high mitochondrial density, express uncoupling protein 1 and possess a metabolic phenotype similar to that of classical brown adipocytes. This plasticity of adipose tissue is regulated by a complex network of transcriptional coactivators (e.g., PRDM16, PGC-1α), epigenetic modulators, non-coding RNAs, and hormonal signals. Environmental cues, such as chronic cold exposure, exercise, and caloric restriction, further potentiate browning via sympathetic nervous system activation and endocrine crosstalk. At the systemic level, adipocyte browning enhances energy expenditure, improves insulin sensitivity, and mitigates lipid accumulation, making it a promising target for the treatment of obesity, type 2 diabetes mellitus, and other metabolic syndromes. Several browning agents (natural products and repositioned drugs) and novel chemicals that induce browning have been reported. However, the translational application of these agents in humans faces challenges related to interspecies differences, depot-specific responses, and long-term safety. This review critically examines molecular regulators, existing browning agents, and the discovery of novel browning agents, with the aim of harnessing them for metabolic disease intervention.