Most fat in human beings appears whitish in color, while brown fat is the mitochondria-packed fat cells that burn energy and produces heat in the body. “It was thought that only babies had brown fat, however, a study found that adults have some brown fat, and people with lower body mass index (BMI) tended to have a higher content of brown fat,” Tucker says. Research has shown that when men are exposed to cooler temps, they have an increase in brown fat—and a corresponding boost in metabolism.
