Fight Fat With Fat – The Skinny On Brown Fat

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We know…it sounds too good to be true. But scientists are are looking into whether we can turn fat against against unwanted flab.

The Fat that BURNS Fat

What difference does colour make when we talk blubber? A lot, it seems, especially if you’re interested in losing it.

In the recent years, scientists have been studying this mitochondria-rich (our cellular energy factories) brown adipose tissue that actually burns energy to generate heat, rather than storing excess calories as fat in the usual ‘white fat’ many of us are reluctantly familiar with.

Brown fat is abundant in rodents and mammals, likely evolved as a source of heat during hibernation as they can’t shiver to warm up. Human newborns have it too, but our stores of this natural fatty furnace seem to get depleted after infancy. In fact, it wasn’t until 2009 that scientists discovered that small amounts of brown fat are still active in adult humans, mainly deep in the body like the neck and along the collarbone and spine.

Another thing researchers realized was that obese people tend to have very little brown fat compared with lean people. Perhaps brown fat may be a back up system for warming the body when all other sources of fuel, including white fat, have been exhausted. But could this lack of brown fat also fit into the obesity puzzle and help to partly explain why obese people are obese?

These game-changing findings ignited much buzz in the medical world, spurring more research to answer the big fat question: “Can we use brown fat to combat obesity, or even battle associated metabolic diseases like Type 2 diabetes?”

Activating Brown Fat – The Secret to a Sizzling Bod?

Most current medically-proven weight loss drugs are aimed at reducing a person’s appetite (like Duromine, and Reductil which has been withdrawn from the market) or impairing intestinal absorption of fat (such as Xenical). Brown fat therapy could potentially represent a brand new class of fat-fighting weapon – one that focuses directly on the unwanted fat and perhaps even help torch excess calories to prevent putting the pounds back on.

In a report in the Journal of Clinical Investigation, scientists found that they were able to chill brown fat in adult men into action by exposing them to cold. Even more promising, the brown fat seems to gobble up white fat (the kind we tend to accumulate in love handles and muffin tops with age) and these men burned more calories (about 250 calories in three hours) at rest by turning down the thermostat.

Knowing that we could mobilize the brown fat as a novel weight loss strategy, the hunt for fat-burning treatments could then focus on activating or growing our brown fat stores without the need to convert our homes into mega fridges.

One such candidate is a hormone called irisin, which increases in both mice and human after exercise. Interestingly, it appeared to turn on genes that may be responsible for browning fat when researchers injected irisin into the white fat of inactive mice, creating “beige fat”. The mice that were injected with the hormone also lost weight and had better blood sugar levels control, compared to mice that were not injected.  What’s even more exciting is the fact that irisin is precisely the same in humans as in mice, which points to the high possibility that humans would enjoy the same benefits from this “exercise shot”.

In another new study published in Cell Metabolism, orexin (a hormone produced by the brain) showed promise as well. Orexin deficient baby mice had impaired brown fat development and also weighed more than their normal counterparts in adulthood, although they actually ate less (a familiar-sounding complaint for so millions of overweight folks). Supplementing orexin allowed the mice to grow brown fat before birth and continued to be active into adulthood. What’s more, adding orexin to stem cells in a laboratory dish caused them to turn into brown fat cells, and raises hope that it can one day be used in humans to prevent or treat obesity.

How Now, Brown Fat?

Could the research eventually lead to an injection that replaces exercise and prevent obesity all together? Not so fast.  The results are still preliminary and the long term consequences are still unanswered. Moreover, even if  “exercise injections” do help you burn calories, they do not make your muscles stronger or strengthen your cardiovascular system unlike good old physical exercise.

Time to hit gym to get your fat-burning engine going!

– By Emily Wong