Brown fat has recently received attention in the media—but in reality it’s not new.  Utilization of brown fat as a treatment for obesity first emerged some 30-40 years ago.  Many in the medical community felt that brown fat didn’t even exist in adults, and so it was quickly abandoned as a possible solution for obesity.  But more recent studies have shed more light on brown fat and its role in obesity and weight loss.

Many of us have heard of brown fat, but most of us aren’t sure what it is or what it does in our bodies.  Babies have brown fat, but it lessens as they grow.  Scientists indicate that adults do have functioning brown fat that is located in the area from the front of the neck to the chest.  It comprises less than 1% of adult body weight.  Brown fat is more abundant in young women, and least abundant in older, obese men, and obese men had less brown fat than non-obese men.  A recent study found that women were twice as likely to have considerable deposits of brown fat.  One possible reason for this is that women have less muscle than men, and therefore need more brown fat to produce heat and stay warm.
 
Scientists have recently determined that brown fat is NOT related to white fat, but rather to skeletal muscle, and once it’s activated through exposure to cold, brown fat burns more calories faster than regular (white) fat.  In other words, brown fat burns calories.  Three ounces of brown fat can burn several hundred calories a day.*

So brown fat decreases as we age, is less present in obese than in normal weight adults, and is activated when time is spend in a cold environment.  The future of utilizing brown fat to enhance weight loss depends on determining a way to activate brown fat, and perhaps even in developing a way to have the body produce additional stores of this substance.  Then we will need to determine whether actually activating brown fat would make people lose weight.  Brown fat could be used as a weight loss strategy since it takes calories from “white fat” and burns it.  Scientists are currently working to develop ways to increase stores of brown fat and increase its metabolism so it will burn calories even faster.  So expect to hear, and read more about obesity, weight loss and brown fat in the future.

*Aaron Cypres, .MD PhD, Joslin Diabetes Center, Boston Massachusetts