S u m m a r y :
Our genetics determine whether a healthy diet will help us lose weight or not, says a new study published in the journal Genetics.
Our DNA Reacts to Food
We are what we eat, a resounding statement that is meant to steer us towards healthy diets. However, this might not be the complete truth. Rather, who we are in essence—our DNA—also affects the way in which our bodies respond to a particular diet, suggests new research conducted by a team of investigators from Texas A&M University. The study shows that there is no such thing as one ideal diet for all of us, as is implied by the dietary recommendations—what is best for one might not be good for another.
“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,” says study senior author David Threadgill. “In the face of the obesity epidemic, it seems like guidelines haven’t been effective.”
Healthy Diets vs Unhealthy Diets
The research is based on 4 animal models of different genetics; it is to be noted that there was almost no genetic difference within any one group, and those between different groups would be similar to differences between 2 unrelated people.
Threadgill and his colleagues have used these models to understand the effects of 5 particular diets on health (the middle 3 deemed healthy):
- An American-style diet (rich in fat and carbs like corn)
- Mediterranean diet (including wheat and red wine extract)
- Japanese (rice and green tea extract)
- Ketogenic diet/ Atkins-like diet (high in fat and protein with very few carbs)
- A control diet
Healthy Diets Can Make Some Individuals Fat
The findings show that while the healthy diets worked well for the majority of the participants, 1 of the 4 genetic types reacted very poorly with the Japanese diet.
“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,” says lead author William Barrington.
Furthermore, the Atkins-like diet did poorly with 2 other genetic types while the other 2 did well. According to Barrington, a genetic strain became very obese, and had fatty livers as well as high cholesterol; another had decreased activity level, and with more body fat, though they also 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,” says Barrington.
American Diet is Bad For Everyone Though
To the surprise of noone, the animal models all did poorly when it came to the American diet: some became very obese, with signs of metabolic syndrome while others had more fat in their liver.
The Mediterranean diet yielded mixed effects: some were healthy while others gained weight, but it was definitely less severe than for the American one.
No One Diet for All
As the results demonstrate, some diets that will make an individual lean and healthy will generate the opposite effect on another.
“In humans, you see such a wide response to diets,” concludes Barrington.
“My goal going into this study was to find the optimal diet,” Barrington said. “But really what we’re finding is that it depends very much on the genetics of the individual and there isn’t one diet that is best for everyone.”
Now, the research team wishes to identify the genes that play a role in one’s response to different diets.
“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.”