Do fat genes actually exist?

By Cindy Kuzma

New health headlines provide a novel excuse for extra pounds: I can’t help it—it’s in my genes. But are “hunger genes”—DNA mutations linked to everything from cravings to a lagging metabolism—the reason you’re overweight?

It’s possible: mutations in a gene called KSR2, for example, produce greater hunger pangs and a slower metabolism in obese people, University of Cambridge researchers say.

And KSR2 isn’t the only gene to blame: a Harvard Medical School study found that one called MRAP2 changes the way your body uses energy. Then there’s FTO, commonly called “the obesity gene”, which regulates levels of the hunger-inducing hormone ghrelin. Two bum copies of FTO could account for up to 6.6 pounds of extra flab, researchers say.

Besides a better understanding of the obesity epidemic—which plagues more than one-third of Americans—these discoveries may eventually lead to new treatments. For instance, ghrelin-lowering drugs could help people with FTO mutations, says Men’s Health nutrition advisor Alan Aragon, M.S.

But focus too much on DNA, and you’ll miss the bigger picture: genes don’t account for every extra pound—they don’t even account for a majority of them, says Dr Robert Ziltzer of the Scottsdale Weight Loss Center. Environment and behavior play a much bigger role in determining your weight, he adds.

While genetic factors—like which versions of FTO you inherited from your mom and dad—do play a role in the development of obesity, they don’t prevent you from dropping pounds, Dr Ziltzer says. That means that the right diet and exercise will lead to weight loss, even in individuals who have obesity in their DNA.

If you really want to know whether you have fat genes, you can find out, at least in part. Go online and you can order tests that, by analyzing a swab from your cheek, tell you if you’ve got chubby versions of the FTO gene. Other companies even say they’ll send you an entire diet and exercise plan tailored to your genetic profile.

But don’t waste your time—or cash, says Aragon. The results don’t change the treatment for obesity. “Gene-based diets outpace science,” he says. We don’t truly know how food and DNA interact long-term. Plus, even if they were completely accurate, you’d still have trouble following a plan that didn’t mesh with your preferences. If your profile says you’ll do best on a low-fat diet, but you love almonds and guacamole, you probably won’t last long, he says.

Instead, design your own diet: eat fewer calories than you burn, and make sure your diet includes a gram of protein per pound of your goal body weight. If you’re aiming for 175 pounds, you should eat 175 grams of protein to shed fat and not muscle, Aragon advises. (Find out how much protein you actually need. Take the test)

Fill the rest of your meals with foods you enjoy eating, focusing on fruits, vegetables, and healthy fats. And keep sweating—a 2011 study showed exercising for at least an hour a week counteracted the effects of FTO variations by 27 per cent.

Related: 10 foods to help you drop weight