The study's authors say it's too soon to give specific diet advice based on their findings, but health experts agree that regardless of your body shape, you'd do well to reduce or eliminate simple sugars and refined foods, like cookies, candy, and sugary sodas. Don't eliminate carbs altogether—even low-glycemic-load dieters got 40 percent of their calories from carbohydrates. Just replace easily digestible carbs with complex ones like fibrous veggies and fruits, brown rice, and whole grains.
Germs: Is Obesity Contagious?
What if your fat is caused not by diet or genes, but by germs—say, a virus? It sounds like a sci-fi horror movie, but research suggests some dimension of the obesity epidemic may be attributable to infection by common viruses, says Dhurandhar.
The idea of "infectobesity" came to him 20 years ago when he was a young doctor treating obesity in Bombay. He discovered that a local avian virus, SMAM-1, caused chickens to die, sickened with organ damage but also, strangely, with lots of abdominal fat.
In experiments, Dhurandhar found that SMAM-1-infected chickens became obese on the same diet as uninfected ones, which stayed svelte. He also found that nearly one in five overweight humans in his Bombay clinic showed antibodies—proving prior infection—and that they were about 33 pounds heavier than those never exposed.
He later moved to the U.S. and onto a bona fide human virus, adenovirus 36 (AD-36). In the lab, every species of animal Dhurandhar infected with the virus became obese—chickens got fat, mice got fat, even rhesus monkeys at the zoo that picked up the virus from the environment suddenly gained 15 percent of their body weight upon exposure.
The virus naturally infects 15 percent to 17 percent of the human population, says Dhurandhar, and is present in 30 percent of obese people—even nonobese people who have it have higher BMIs than their uninfected peers. "Even within that group, they were fatter," says Dhurandhar. "It could mean that's how they'll stay, or it could mean they were pre-obese."
For people who want to know whether they're infected, a Richmond, Virginia, company called Obetech offers an AD-36 antibody test. Although there's no way to rid your body of the virus, what the test can give you is a warning flag: If you find out you're infected, you can start eating healthfully and exercising now to try to stave off obesity later.
In his latest studies, Dhurandhar has isolated a gene that, when blocked from expressing itself, seems to turn off the virus's fattening power. Stem cells extracted from fat cells and then exposed to AD-36 reliably blossom into fat cells—but when stem cells are exposed to an AD-36 virus with the key gene inhibited, the stems cells don't differentiate. The gene appears to be necessary and sufficient to trigger AD-36-related obesity, and the goal is to use the research to create a sort of obesity vaccine.
Researchers have discovered 10 microbes so far that trigger obesity—seven of them viruses. It may be a long shot, but for people struggling desperately to be thin, even the possibility of an alternative cause of obesity offers some solace. "They feel better knowing there may be something beyond them that could be responsible," says Dhurandhar. "The thought that there could be something besides what they've heard all their lives—that they are greedy and lazy—helps."
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