Study: Diet Success Depends on Your Genes


A diet that makes one individual lean and healthy might have the complete opposite effect on another, according to a new study published in the journal Genetics.

One diet doesn’t fit all, and what works for some may not be best for others. Image credit: Rita E.

“Dietary advice, whether it comes from the U.S. government or some other organization, tends to be based on the theory that there is going to be one diet that will help everyone. In the face of the obesity epidemic, it seems like guidelines haven’t been effective,” said study senior author Dr. David Threadgill, from the Texas A&M College of Medicine and College of Veterinary Medicine & Biomedical Sciences.

Dr. Threadgill and his colleagues from Texas A&M University, North Carolina State University, Research Diets, Inc., Johns Hopkins University, and Universities of Tennessee and North Carolina used four different groups of animal models to look at how five diets affect health over a 6-month period.

The genetic differences within each group were almost non-existent, while the genetics between any two of the groups would translate to roughly the same as those of two unrelated people.

The researchers chose the test diets to mirror those eaten by humans:

(i) American-style diet: higher in fat and refined carbs, especially corn;

(ii) Mediterranean diet: with wheat and red wine extract;

(iii) Japanese diet: with rice and green tea extract;

(iv) ketogenic, or Atkins-like, diet: high in fat and protein with very few carbs;

(v) fifth diet was the control group who ate standard commercial chow.

Although some so-called healthy diets did work well for most individuals, one of the four genetic types did very poorly when eating the Japanese-like diet, for example.

“The fourth strain, 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 William Barrington, from North Carolina State University.

“A similar thing happened with the Atkins-like diet: two genetic types did well, and two did very badly. One became very obese, with fatty livers and high cholesterol.”

“The other had a reduction in activity level and more body fat, but still remained lean.”

“This equates to what we call ‘skinny-fat’ in humans, in which someone looks to be a healthy weight but actually has a high percentage of body fat.”

“In humans, you see such a wide response to diets. We wanted to find out, in a controlled way, what was the effect of the genetics,” he said.

The authors measured physical signs, especially evidence of metabolic syndrome, which is a collection of signs of obesity-related problems, including high blood pressure and cholesterol, fatty liver and levels of blood sugar.

They also studied any behavioral differences, from how much they moved around to how much they ate.

“We wanted to get the diets as close to popular human diets as possible. We matched fiber content and matched bioactive compounds thought to be important in disease,” Barrington said.

Perhaps as could be expected, both in earlier research and in anecdotal evidence in humans, the animal models tended not to do great on the American-style diet.

A couple of the strains became very obese and had signs of metabolic syndrome. Other strains showed fewer negative effects, with one showing few changes except for having somewhat more fat in the liver.

With the Mediterranean diet, there was a mix of effects. Some groups were healthy, while others experienced weight gain, although it was less severe than in the American diet.

Interestingly, these effects held, even though the quantity of consumption was unlimited.

“Our future work will focus on determining which genes are involved in the response to the diets,” the researchers said.

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William T. Barrington et al. Improving Metabolic Health through Precision Dietetics in Mice. Genetics, published online November 20, 2017; doi: 10.1534/genetics.117.300536

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