Posted on 02/23/2011 at 03:30:14 PM by Student BloggerBy: Gopi M.K.
Cold weather has a way to kindle slack in most of us. Come winter, my running schedule comes to a halt and I end up swaddled in layers of fabric like a big heap - just like my unspent calories. I used to fret about the fattening storm inside me until I came across brown adipose tissue (BAT) and I realized that the cold isn't bad. A new view about fat became apparent and it was so cool that it was hot (pun intended).
Fat is primarily stored as large lipid droplets in the cells of white adipose tissue and a surfeit of this tissue has become synonymous with obesity and the associated metabolic syndrome. BAT, on the other hand, is more of a fat incinerator than a fat depository, in that it burns fat to generate heat to maintain the core body temperature in infants and small mammals. In adults, it was thought to be absent or vestigial until two years ago, when studies confirmed the formation and presence in humans in response to cold temperatures. Functionally active BAT was found below the shoulder blades and an increase in energy expenditure during rest was observed when the subjects were exposed to cold temperatures (1). All you need to do is treat winter as summer and you could burn calories without a bead of sweat! While it is not as simple as it seems, BAT has opened exciting possibilities for modulating energy expenditure.
While mild cold weather serves us good by activating BAT and burning energy, statistics suggest a direct correlation between obesity prevalence and winter domestic temperatures in the US and UK (4). The indoor temperatures rose steadily in the last few decades and so has the body mass index (BMI). Thus, as we reside more in our thermal comfort zones and spend energy we are not actually spending energy. By turning down the heater we could pride ourselves as altruists while at the same time doing ourselves a favor.
A twist however, is the negative correlation between BAT and body fat percentage, body mass index and old age (5). Unfortunately, these are the very groups ravaged by all the morbidities associated with being overweight. Obesity is not just a burden to the individual, but is a looming public health catastrophe in many nations. This is more so for developing nations, which are just beginning to see improved standards of living and the population is mostly young. Once the bulge sets in and the population is significantly older, the possibilities look grim. At this juncture, while there are many questions about BAT and how best to use it, take my cue, join me, and stay cool. Fight fat with fat!