There's fat and then there's fat

For the past few years I've heard passing references to brown fat and white fat, but never understood the difference between them. Today I read The Wall Street Journal's "Personal Journal" section and saw an article that finally clarified the two kinds of fat for me. It also led me to believe there may be developments coming in the field that could potentially (lots of qualifiers there) help our obese and overweight population.

So let's go back to the kinds of fat. Brown fat is different from the kind we tend to accumulate arround our mid-sections as adults if we eat too much and/or exercise too little. It's actually brown in color, found in babies, and contains lots of the heat-producing little cellular "engines" called mitochondria. Little kids are more at risk for hypothermia than adults, so they have more brown fat as a protective mechanism.

Can we use this natural calorie-burning mechanism when we're overweight? In a variety of places researchers are attempting to solve this question. One mechanism for revving up brown fat, at least in mice, appears to be exposure to cold. Some studies have shown that humans may adapt to cooler temperatures by increasing the amount or activity of brown fat, but we're a long ways from anything definitive.

The question isn't as simple as it may seem. Lean men seem to respond better than obese men to exposure to cold, at least in terms of brown fat activation. A map of the United States in another article showed obesity, in general terms, to be more prevalent in the Southeast, but many factors may contribute to that finding.

Harvard and MIT teams are attempting to find a way to produce more brown fat by activating a protein called PRDM16. Their initial work is near completion, but development of an actual marketable drug that works in this fashion is at least five to ten years away.

So in the meantime, should we all turn our thermostats down to say 65 degrees. I think that's a good idea; it would save fuel, decrease our emissions perhaps (thereby helping prevent global warming), and maybe, just maybe help us to lose a few pounds.

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