Contemporary obesity rates have never made much sense to me: there are too many just-so stories to explain it. And all of them seem to feature bad guys wearing black hats: gluten, agribusiness, high fructose corn syrup, weak morals, and so on.
A somewhat different one that’s always gotten me is that obese people aren’t getting enough exercise. Every spent some time around an obese person? The heavy breathing, sweating, and weariness look to me a whole lot like they’re getting more exercise doing normal things than the rest of us are.
All of this raises a provocative question. “It is so accepted that obesity is bad for you, but why is it bad for you?” Dr. Virtue says. “If I put a 50-pound weight on your back and asked you to walk around all day, you would be a superhealthy person.”
Continuing research on leptin (you know, the hormone they made the hugely fat mice with years ago) is pointing in new directions. But it isn’t leptin that’s the direct issue. Instead, it’s the amount of fatty tissue people have.
Fat people develop metabolic disorders because their brain is driving them to eat more food than their bodies can store as fat. Their fat tissue has reached its limit. …
This is also why some people find that their metabolic disorders improve with just a small weight loss — they are eating less and their fat tissue can respond properly.
It also explains why 10 percent to 20 percent of obese people never develop metabolic disorders, Dr. Scherer said. These so-called healthy obese are like his fat mice, with an unusual ability to expand their fat tissue to store calories.
A good hallmark of something that isn’t a just-so story is that it provides a symmetrical explanation. In this case, obese people without metabolic disorders are those with more fatty tissue to begin with, while thin people with metabolic disorders are those with less fatty tissue to begin with.
Do note that I keep writing “fatty tissue” rather than fat. Fatty tissue stores fat properly so that it doesn’t make the body sick. So if your fat storage works properly, and there’s enough of it … you don’t get metabolic syndrome.
And here’s some totally weird supporting evidence:
… The mice … had almost no fat tissue. And like her, they developed all of the conditions associated with obesity.
What would happen, the researchers asked, if the mice had a bit more fat tissue?
They transplanted fat tissue into the rodents, and two weeks later, the mice had normal levels of glucose, insulin and triglycerides. Their livers and muscles went back to normal, too.
If that worked, the scientists wondered, could a limitless amount of fat tissue prevent the syndrome, even if copious amounts of fat were stored in that tissue?
… They engineered mice that could make an almost limitless amount of fat tissue. As a result, there was no end to the amount of fat the animals could store. They were, Dr. Scherer said, “the fattest mice under the sun, the mouse equivalent of an 800-pound human being.”
The fat mice were metabolically normal.
Read the whole thing, entitled “Skinny People with Obesity Issues? A Rare Window for Researcers” in the July 22 issue of The New York Times.
P.S. Sorry. But I think the obese mice are cute, and had to include a picture for no other decent reason.