HOW NOW BROWN ... FAT?

We all want more of the good fat babies are born with, writes

For several years now, researchers have been trying to find ways to plumb the potential of the lesser known “brown fat”, or BAT, the adipose tissue that keeps babies warm before they’re old enough to shiver, and which was once (mistakenly) thought to dissipate entirely over the course of childhood. In contrast to the white fat we’re all so keen to exorcise from our lipid-laden bodies, recent studies have found that brown fat is practically anathema to diseases such as type 2 diabetes and congestive heart failure: in response to some very specific stimuli, brown fat speeds up the rate at which we consume our reserves of the white fat responsible for these maladies.

This revelation has encouraged some medical specialists in the field of obesity research to laud brown fat as the breakthrough cure-all they’ve been waiting for, but the — predictably disappointing — counterpoint is that getting the brown fat itself on board with our weight-loss agenda requires some strange manoeuvring, both on the part of scientists and their denuded test subjects.

Still, this hasn’t deterred brown fat enthusiasts from staging a variety of trials in a bid to home in on brown fat’s latent potential.

Cold comfort

Structurally and behaviourally distinct from the white fat that collects around our guts and organs, brown fat is found in (relatively scant) reserves around our necks, spines, and collarbones. Its main fascination for the medico-scientific community at this point is that, when our bodies register extreme drops in temperature, brown fat initiates a chemical response that ultimately spikes the body’s metabolic rate — we expend the energy stored in our white fat more quickly as the body works to restore equilibrium.

The problem for slothful, snug laymen such as myself is that, by the time most people reach maturity, they have little to no brown fat left. Because we spend the greater part of our lives in temperature-regulated environs, we simply haven’t had need of it. But new studies have found that exposure to extreme cold can actually precipitate the production of all-new brown fat, which, according to an article in Scientific American, compelled the engineers of a 2012 study to stick six stationary men in “cold suits” for three hours at a time.

The Hof

In a promising turn of events, researchers found that their frigid volunteers had each consumed 250 calories more than they would have done in sitting still in a temperate space. Similar trials have supported the hypothesis that repeated exposure to extreme cold can supplement extant stores of brown fat; and still more studies support the view that the presence of brown fat can engender weight-loss, lower cholesterol and correct high blood pressure.

Naysayers have pointed out that it’s not all that easy to identify and monitor the presence of brown fat in the body: doing so usually entails a PET-CT, a visual scan that requires that its subjects be injected with a shot of radioactive sugar molecules.

White fat cells consist of unified, waxy blobs; brown fat cells contain several blobby pockets as well as the eponymous chestnuthued mitochondria responsible for initiating the fat-burning process when our bodies get cold. The mitochondria in the brown fat cells emit gamma rays when they start consuming the irradiated sugar; the gamma rays can be seen on the scan, thus illuminating the location of the brown fat in the body.

Strictly speaking, PET scans aren’t enormously dangerous, but they’re also not safe enough to be recommended for routine usage on otherwise healthy people.

Other detractors have reminded BAT enthusiasts that, unless people are prepared to model their lifestyles on that of extremecold enthusiast Wim Hof, they are not likely to have enough brown fat to redress the problems arising from its pallid nemesis.

An article on brown fat in the Guardian cites a 2008 study that found that Hof — the quasi-mythical Dutch extreme athlete famed for withstanding freezing temperatures on a regular basis — is capable of generating five times more heat energy than your average tepid 20-year-old, ostensibly because of his comparatively enormous stores of the good (brown) stuff.

This is wonderful news for Mr Hof (and lucrative fodder for his lifestyle brand), but it’s true that most of us aren’t going to endure more than a semi-regular coldwater shower in a bid to coax our brown fat out of retirement.

Brite future

Some scientists are already looking ahead to a novel solution: the development of “beige fat”, or “brite” — hybridized white fat cells that could theoretically be manipulated into behaving more like their useful brown counterparts.

But, as professor Michael Symonds, a brown fat expert at the University of Nottingham in the UK, concedes, having too much “active brown fat” would make us very uncomfortable: side-effects might range from profuse, interminable sweating to feeling always and irredeemably hot.

On balance, even though it might be better for us to set the possibility of “brite” aside for the time being and concentrate on more conventional healthfulness instead, it’s nice to know that the next time your geyser bursts or we have a bout of loadshedding, all those cold showers might actually be doing you a favour.