Diet not working? Blame your genes. That's the pitch behind a new test that claims to show whether people will do better on a low-fat or a low-carb weight loss plan.
We're all hard-wired with DNA that controls how we burn and store calories from various foods, and the test claims to sort out this machinery. A study this week found that women on diets well-matched to their genes, as defined by the test, lost roughly five times more weight than those on mismatched diets.
"We were able to explain why some people were successful" and others were not, even though they ate the same way, said Mindy Dopler Nelson, a nutritional biologist at Stanford University who led the study but has no financial ties to the maker of the test.
Some scientists find this hard to swallow. It's another test being peddled without enough research to show it really works, they say.
"I'm afraid this may be another attempt to lure the public into purchasing genetic tests that provide little value for those struggling with their weight," said Raymond Rodriguez, director of the National Center of Excellence for Nutritional Genomics at the University of California, Davis.
The research shows "nothing that should move the American public out to get their genome tested," said Robert Eckel, a former American Heart Association president and cardiologist at the University of Colorado-Denver.
But it sure has appeal.
Gene testing originally was aimed at finding risk for things like cancer, diabetes and Alzheimer's disease. Lately, genes have been linked to things you might not suspect, such as stuttering or compulsive leg-jiggling.
The latest trend is to connect genes to lifestyle counseling, determining what type of diet or exercise is best. That's what the maker of the new diet test hopes to do.
The company, Waltham, Mass.-based Interleukin Genetics Inc., looked at studies on hundreds of genes and chose three genes that show a pattern for metabolizing fats and carbohydrates, said its chief scientific officer, Ken Korman.
The company then hired Stanford researchers to do a validation study of its $149 test, using people who took part in diet research that was published in 2007. That study tested four diets — Atkins (ultra-low-carb), the Zone (low-carb), Ornish (very low-fat) or a low-fat diet following the federal Food Pyramid.
Some scientists were unpersuaded by the study's results. Sticking with a diet is more important than what diet you choose, as is not regaining weight, Eckel said.