Skinny Genes: DNA Diet Plans


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Dansinger coauthored a well-known study in The Journal of the American Medical Association comparing the Atkins, Ornish, Weight Watchers, and Zone diets and reported, similar to Stanford, that none of them was better than any other. The only factor that mattered was whether people stuck to their diet, and Weight Watchers and the Zone, the more moderate of the bunch, had the best adherence. So, Dansinger reasons, the ideal diet isn't in your genes; it's the one that fits your food preferences and lifestyle.

The Hunter/Farmer Diet Solution, a new book by Mark Liponis, MD, the corporate medical director of Canyon Ranch Health Resorts, is founded on the idea that body types, evolved over millennia, fall into two basic groups: the hunter (who does better with limited carbs) and the farmer (who should opt for a low-fat, grazing-style diet). Our body types are genetically determined, he says, but not just by inheritance. Everything from what happened while we were in our mother's womb to environmental and other stressors interacts with our genes and causes some biological tendencies to be expressed more than others, Liponis argues. Instead of ordering tests, he says that he prefers to look at the way a patient presents in his office and offers a simple list of questions to assess health risks and dietary obstacles: Are you apple or pear shape? Are you hungry all the time? Crave sweets? What are your blood lipid levels? How about fasting glucose? He'd need a genetic test only to determine what diet to recommend for patients so healthy and thin that they don't have any markers for disease. But then, Liponis points out, "If someone is healthy and thin, they're probably naturally doing the right things, so why put them on a diet?"

The scientists behind Interleukin and Newtopia, not surprisingly, disagree with such critiques. "We do not for a second claim that this is the end-all, be-all of genetics in body weight," says Kenneth Kornman, president and chief scientific officer of Interleukin. "But our data clearly indicate that if people have a diet that matches their pattern, the likelihood of success is significantly greater in terms of long-term weight loss than if they're just out there randomly picking diets."

Jeff Ruby, founder and CEO of Newtopia, concurred with Dansinger that the genetic contribution to weight is much smaller than lifestyle. But, he said, every bit helps when you're trying to do something as hard as shed pounds and keep them off.

Finally my results came in. Of the five genetic variations tested by Interleukin, I carried four of the high-risk ones. Of Newtopia's three, I carried a risk variation in two. I was stunned. I checked with the companies to see if maybe these were genes that, in truth, everyone carries. But no, the incidence among Caucasians (I'm white) ranged from about 20 percent to 30 percent. I e-mailed a friend who'd also tried one of the tests and describes herself as perpetually "chubby," and yet, she wrote back, she carried only one of the danger genes.

Reading the literature on my genetic variations, I found alarming evidence of increased risk for obesity and its complications: cancer, diabetes, heart disease. Both companies recommended a low-carb diet, but I've been a vegetarian or vegan for long stretches of my adult life. Had I been doing harm to my blood glucose levels and arteries? Later in life, would my waistline bulge, my blood pressure soar?

Nobody from either company seemed ruffled to learn I was relatively fit despite being riddled with obesity genes. Newtopia's Ruby said he had the exact same genetic profile as I did and also had never had a weight problem. "It's not that you're predetermined to gain weight, it's just that you have genetic vulnerabilities," he said. He and Kornman both said I was likely living a far healthier lifestyle than I gave myself credit for. When I thought about it that way, I stopped feeling so bad about my genes and started patting myself on the back for my healthy ways. I'm a very consistent exerciser, I thought, and my mother is a nutritionist, so I was raised in a house without Doritos or Coke, one where vegetables dominated every meal and crash dieting was forbidden—maybe the effects were more durable than I'd realized.

So was my blond friend right? Should we blame our epidemic of obesity on bad habits alone? "It's not true either way," said Wendy Chung, MD, PhD, an assistant professor of pediatrics at Columbia University and an expert on genetics and obesity. We'd spoken earlier, and now, as I breathlessly read off my results to her, she couldn't help but giggle. "I'm sorry, I'm not laughing at you. I'm just laughing at how predictable this was. I told you that you'd get back gibberish!" Since scientists have so far turned up about 200 genes involved in body weight, how could testing for eight variations be useful? "What about the other 180 or so?" Chung said. "They could say something totally different. Tell your readers not to waste their money or time. I feel bad because I know there are a lot of desperate people, but this is just a total scam."

Robert Eckel, MD, professor of cardiology at the University of Colorado School of Medicine, took more of a wait-and-see approach. When Dansinger's paper comparing popular diets came out in 2005, Eckel wrote an accompanying essay suggesting that "nutrigenomics" might be the future of weight loss but "at present, there are no data to help clinicians practicably match a diet to an individual patient's `diet response genotype.' " Though he was aware of Interleukin's collaboration with Stanford, he said that his stance has not changed. The data the companies are relying on first must be published, then validated by other scientists. "There might be some value here, it's just not ready for prime time," he said. "When we're talking about medicine, I like to make recommendations based on evidence. But some people like to gamble, and sometimes they win the jackpot. In gambling terms, this is still a long shot."

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