Adipocytes are a major hub for energy balance and fuel metabolism in the body. Inter- and intra-depot heterogeneity of adipocytes offers a wide range of functional diversity enabling short- and long-term regulation of energy storage and dissipation. White adipocytes store energy in the form of triglycerides in lipid droplets and are found in discrete white adipose tissue (WAT) depots, as well as dispersed in other tissues throughout the body. Excess WAT is associated with insulin resistance and metabolic syndrome. Brown and beige adipocytes, on the other hand, are specialized to burn energy and generate heat. Classical brown adipocytes are present in a distinct brown adipose tissue (BAT) depot, while beige/brite adipocytes appear intermixed in WAT depots, where they are induced or activated in response to certain environmental cues, such as chronic cold exposure, exercise training, or pharmacologic treatment with the β-adrenergic receptor activators. In general, increased brown/beige fat is associated with improved metabolic health.