One of the most exciting finds in modern obesity research was the influence of brown fat stores in the human body. Brown fat is unlike regular or white fat in that rather than being primarily a storage depot for excess energy, it has a high metabolic activity potential. In fact, the brownish color probably comes from blood flow and chemicals within the cell that aid metabolic activity.
Brown fat has been studied in animals for some time. Found mostly in hibernators after the long hibernation period and as a “metabolic warming blanket” against cooling of the body in a cold environment. This tissue in animals is full of blood vessels and has such a high metabolic rate that in rats it can account for a five-fold increase in resting heat production. It can also hypertrophy and become more effective if needed.
Although not as much is known about the role of brown fat in humans, there is evidence that the obese have less total brown fat storage and that is much less active. Obviously, at least some excess energy could be “burned” in this “heating blanket” of metabolically active tissue and this energy would then be released as heat rather than stored as fat.
Apparently, this is one of the reasons that then people who eat a lot stay thin. In fact, these people may actually increase their brown fat stores so that they can waste more and have more energy. On the other hand, people who have a poor supply of or inactive brown fat may store fat effectively because there is no brown fat to waste it.
Another reason why brown fat becomes inactive is because we wear clothes. Primal humans were exposed to the elements and were not always covered. The need for brown fat was great because it acted as a heating mechanism. As humans became more civilized and lived in heated shelters and wore clothing to protect them against the outdoor temperatures, the development of brown fat decreased. You can notice this with babies and kids. Mothers are always telling their kids to put on a jacket before going out into the cold temperatures. The kids are not cold, in fact if you put your hand on the middle upper back region of the child you can feel heat radiating from the area. The heat comes from the brown fat. There is a lot of brown fat around the thoracic area to help protect the lungs and heart. Unfortunately, this great heating mechanism gets decreased when jackets are worn.
There is still more to know about brown fat, but all that I know is that brown fat provides great benefit to the body.
Daryl Conant, M.Ed.