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Gina Kolata had a New York Times article last week about “brown fat” — the strange, recently discovered (in adult humans, at least) type of fat that burns lots of calories:
A new study finds that one form of it, which is turned on when people get cold, sucks fat out of the rest of the body to fuel itself. Another new study finds that a second form of brown fat can be created from ordinary white fat by exercise.
So what does this mean? No one is really sure at this point, since it’s only been a couple of years since we even realized that it existed in adult humans. Do people become obese because they lack brown fat? Or do they lose brown fat when they become obese? Or does it just seem as if obese people have less brown fat because they don’t get as cold as leaner people, so their brown fat remains dormant? We don’t know.
Still, the article made me think of a pair of posts I wrote last year (here and here) about research that linked the rise in obesity rates with a parallel rise in the typical thermostat settings in U.S. and U.K. homes. Could the warmer ambient temperatures that we expect these days have anything to do with higher rates of obesity? There are many reasons to be highly skeptical about this idea… but the fact that brown fat turns on and starts plowing through calories at colder temperatures does provide a plausible mechanism — beyond shivering — for how temperature could play a role.
Of course, researchers say, they are not blind to the implications of their work. If they could turn on brown fat in people without putting them in cold rooms or making them exercise night and day, they might have a terrific weight loss treatment. And companies are getting to work.
We don’t really need to wait for “companies to get to work,” though. We already know how to trigger brown fat without any pills: even if you don’t go for turning down the thermostat (and I don’t believe there’s anywhere near enough evidence to advise that), the other option — exercise — sounds like a pretty good idea.
Of course, if you turn down the thermostat a bit you have the advantage of saving energy and money, which are two good reasons I’d say.
It seems to me brown fat has been known for 20+ years. I remember a film when I was in training as a dietitian which discussed using as an example a woman who could not lose weight unless she cut her calories way down (I think around 600). It seems to me that the researcher was showing her as having very little brown fat. I think the research was English, but it also seems to me that I did not hear of it again till now.
I remember seeing a Nature of Things programme investigating brown fat around 1982! That David Suzuki, always ahead of his time.
I hate to take that side of the debate but telling people to get off their fat asses and exercise has not exactly been an easy sell for the past 30-40 years. That we have yet another reason to do so will hardly matter.
Suzuki ahead of his time? That man might have been a good geneticist but so-so outside his field.
We’ve known about brown fat (basically adipocytes that express UCPs (uncoupling proteins)) for a while. Their presence in adults is kinda neat, though!