Why Your DNA May Be Sabotaging Your Diet

For diets that haven’t worked out as planned, would-be weight-losers may have something to blame other than a lack of effort. It could be in their DNA.

New findings from researchers at Texas A&M discovered that, in animal studies, the results of a specific diet – whether it’s an American-style diet or the highly touted Mediterranean diet – vary widely depending on the composition of the underlying genetics.

The researchers tested five types of diets on mice, dividing the animals into four groups based on similarities in DNA. Mice within the same group had almost the exact same genes, while those genes differed from animals in the other three groups.

Dividing the mice into DNA-similar groups allowed the researchers to test how various diets affected groups differently. They studied five types of diets among each of the groups, including an American-style diet, a Mediterranean diet, a Japanese diet, an Atkins-based diet and a control diet.

The American diet contained higher levels of fat and processed carbohydrates, while the others had key characteristics, such as wheat and red wine in the Mediterranean diet; rice and green tea in the Japanese diet; few carbohydrates in the Atkins diet; and normal mouse food in the control diet.

Ultimately, the researchers found that a diet that’s generally considered healthy, the Japanese diet, had beneficial results among most groups – but not all of them.

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“The fourth [group], which performed just fine on all of the other diets, did terrible on this diet, with increased fat in the liver and markings of liver damage,” said lead author Dr. William Barrington.

Other diets performed in a similar way, with some animal groups seeing benefits and others reaping poorer health results. For example, two groups had positive results from the Atkins diet, and two others didn’t fare as well. “One became very obese, with fatty livers and high cholesterol,” Barrington said.

The researchers had hoped at the outset of the study to find a widely beneficial diet for humans, but their work suggests that people seeking to lose weight may be up against an unanticipated foe – their own DNA.

Dietary Guidelines: More Personal Than We Thought

The researchers float the idea of “precision dietetics,” or an approach to personalized eating or dieting that considers someone’s underlying genetics, according to the study.

The new findings appear to overturn conventional wisdom about healthy eating when taking whole swathes of people into consideration.

“Dietary advice, whether it comes from the United States government or some other organization, tends to be based on the theory that there is going to be one diet that will help everyone,” said senior author Dr. David Threadgill. “In the face of the obesity epidemic, it seems like guidelines haven’t been effective.”

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For the study, researchers found that the American-style diet tended to result in poor outcomes among the animal groups, with reports of obesity and other health problems. Even the Mediterranean diet had mixed results, although the researchers say that weight gain under this diet was not as severe as the American-style diet.

While the researchers didn’t identify specific genes tied to the effects of one diet or another, they hope to do so in the future.

“One day, we’d love to develop a genetic test that could tell each person the best diet for their own genetic makeup,” Barrington said. “There might be a geographical difference based on what your ancestors ate, but we just don’t know enough to say for sure yet.”

Richard Scott

Richard Scott is a health care reporter focusing on health policy and public health. Richard keeps tabs on national health trends from his Philadelphia location and is an active member of the Association of Health Care Journalists.

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