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Is Genetic Testing for You?

The new DNA diet breakthroughs

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I admit it: I’m not a big fan of getting nutrition information from popular magazines. But I am a fan of Dr. Mehmet Oz, who once spent an hour interviewing me on his Oprah and Friends radio show. This is why a recent magazine headline-“Dr. Oz’s Diet Breakthrough!”-caught my attention.

Dr. Oz was quoted as saying that when you match your diet to your DNA, you get better results.

The overarching principle of a “DNA Diet” is that people are metabolically, hormonally, and genetically unique. That notion is 100 percent correct. And it certainly stands to reason that individual differences account for a big part of why some people (but not all) thrive on Atkins, some people (but not all) do OK as vegetarians, and even others find Snooki and Justin Bieber endlessly fascinating.

But determining what the variables that account for our differences are-and how to measure them-has proved difficult. William Wolcott tried it with Metabolic Typing. Peter D’Amato tried it with his famous Blood Type Diet. Joseph Mercola recently tried it with a system called Nutritional Typing designed by my colleague Glen Depke. All attempt to find information that will let us match the “right” diet to the “right” person. Enter genetic testing.

Is gene testing accurate?

A bunch of companies have recently sprung up offering relatively inexpensive DNA testing, the purpose of which is to help you find the diet that’s right for you based on your genes. The theory is that genetic testing can help predict which people will respond best to a low-fat diet, which people will respond best to a low-carb diet, and which people will do best with a diet somewhere in between. Sounds like a good idea, right?

Well, maybe. The big critique here is that these companies test for a handful of genes out of the some 30,000 genes in your body. The companies that market the testing tell you that the genes they test for are the most important ones for determining diet. But really, what else would you expect them to say? No one actually knows exactly what genes are most important for determining the right fit between person and diet.

Nonetheless, there is something to the idea that some people respond much more positively to certain diets than others. And that if you could only figure out in advance who was, for example, an “Atkins person” versus a “low-fat person,” you could get much better success (and save a lot of time and frustration) because you’d match the person to the dietary strategy to which they were best suited.

The DNA diet experiment

The DNA diet that Oz is talking about got a bit of a boost in credibility because of a study done a couple of years ago called “The A-Z Weight Loss Study,” in which researchers at Stanford University pitted the Atkins, Zone, Ornish, and the high-carb LEARN diets against each other. There is a great video presentation on the study on youtube. It’s an hour long, but riveting-well worth the time. To see it, go to and search “The Battle of the Diets: Is Anyone Winning (At Losing?)”

Christopher Gardner, lead researcher of the original A-Z Diet Study and an associate professor of medicine at Stanford, has noted that there were subgroups in every one of the four diet groups that did particularly well, outperforming the average for their group. For example, those with insulin resistance did much better on low-carb plans and much worse on the low-fat plans, which is hardly surprising.

In a very clever follow-up test, researchers administered genetic tests to the participants after the study was over. They then went back and looked to see whether those participants who had been accidentally assigned to their “right” diet actually did better (lost more weight) than those who were not well matched to their diet.

In other words, did people whose genetic tests showed they would be a good fit for Atkins actually lose more weight with Atkins? Did people whose genetic tests showed they’d be better with low-fat actually do better with low-fat?

The results

The answer is yes. According to the press release from Stanford University and Interleukin Genetics, those on genotype-appropriate diets lost 5.3 percent of body weight compared with individuals on diets not appropriate to their genotype who lost only 2.3 percent of body weight.

So does this mean you should run out and get your DNA tested? Not necessarily. As mentioned, there’s a lot of criticism about gene testing revolving around how woefully incomplete it is. And you may be able to get just as valuable information by taking a simple nutritional typing test such as the one by Glen Depke that I reproduced in my book The 150 Most Effective Ways to Boost Your Energy.

The take-home point: Everybody’s different. If one diet doesn’t work for you-and you’ve given it a true and honest try-try something else. Remember, the best weight loss diet is the one you actually follow and the one you feel best on.