Understanding the Biology of Thermogenic Fat: Is Browning A New Approach to the Treatment of Obesity?

Obesity is characterized by an excess of white adipose tissue (WAT). Recent evidence has demonstrated that WAT can change its phenotype to a brown-like adipose tissue known as beige/brite adipose tissue. This transition is characterized by an increase in thermogenic capacity mediated by uncoupling protein 1 (UCP1). This browning process is a potential new target for treating obesity. The aim of this review is to integrate the different mechanisms by which beige/brite adipocytes are formed and to describe the physiological, pharmacological and nutritional inducers that can promote browning. An additional aim is to show evidence of how some of these inducers can be used as potential therapeutic agents against obesity and its comorbidities. This review shows the importance of brown and beige/brite adipose tissue and the mechanisms of their formation. Particularly, the two theories of beige/brite adipocyte origin are discussed: de novo differentiation and transdifferentiation. The gene markers that identify these types of adipocytes and the involvement of microRNAs in the epigenetic regulation of the browning process is also discussed. Additionally, we describe the transcriptional control of UCP1 expression by some of the inducers of browning. Furthermore, we describe in detail how some bioactive dietary compounds can induce browning and their subsequent beneficial health effects. The evidence suggests that browning is a new potential strategy for the treatment of obesity and obesity-associated metabolic disorders.