May 23, 1980

Blame it all on brown fat now

JAMA. 1980;243(20):1983-1985. doi:10.1001/jama.1980.03300460003001

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Physicians and nutritionists who have long preached that overeating must unavoidably lead to obesity may have to revise their sermon if a newly emerging theory about the mechanism of obesity is confirmed.

Results of recent animal and human studies now strongly suggest that body weight is not always directly related to the amount of food one eats. Instead, researchers speculate, some obesity may result from an inability to burn off excess calories as heat, leading to storage of these calories as fat.

The new theory of obesity is based on the study of the body's small store of heat-producing adipose tissue, called brown fat because its high cytochrome content gives it a brownish tint. It has long been known that a higher food intake results in a higher metabolic rate and a higher rate of heat production in tissue; researchers now believe that the site of this type of thermogenesis