If you struggle with weight loss, you’ve probably tried numerous diets without success, perhaps losing some weight only to gain it back again, even when eating moderately. Your inability to lose weight may not be your fault, suggests a new study. Your genetics may be to blame for your body’s lack of response to certain diets.

The research, on mice, showed that one diet doesn’t fit all, and what works for some may not work for others.

The results show how a diet that is good for one group of mice — or people — may not work, or work as well, for another group.

“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,” David Threadgill, senior author of the study, explains. “In the face of the obesity epidemic, it seems like guidelines haven't been effective.”

So the Texas A&M College of Medicine researchers set out to find out why. They used four different groups of mice to study the effect of five diets over a six-month period. Within each group there were barely any genetic differences, but the genetic differences between any two of the groups were considerable — much like those of two unrelated people.

The test diets were similar to those eaten by humans. One group was fed an American-style diet, high in fat and refined carbs, particularly corn. Three other groups were fed diets considered to be healthier: the Mediterranean diet featuring wheat and red wine extract; a Japanese diet with rice and green tea extract; and an Atkins-like ketogenic diet, high in fat and protein with very few carbs. The control diet was standard commercial mouse chow.

As expected, the mice eating the American diet did not do so well. Some became obese and showed signs of metabolic syndrome. Others exhibited fewer negative effects, except for those that developed more fat in the liver. On the Mediterranean diet, some mice were healthy while others gained weight, though not as much as those eating the American diet did, despite being able to eat as much as they wanted.

One group of mice did very poorly on the Japanese diet, with signs of liver damage. Two groups of the mice eating the Atkins-like, ketogenic diet did well; but another group became obese, developed high cholesterol and fatty livers, and another became “skinny fat,” just as some people do. They looked lean but actually had a lot of body fat and high cholesterol.

The results indicate that a diet good for one group of mice — or people — may not work, or work as well, for another group. There just isn’t a “one size fits all” diet for weight loss.

Needed next are studies to determine which genes are involved in how a body responds to various diets.

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

Stay tuned. This could get interesting.

The study is published in Genetics.