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Being overweight is a hefty problem in the United States, affecting approximately 1 in 6, or 39.8 million American adults. And it seems as if there are at least that many different diets or weight-loss products to choose from.
So, how do you find a plan that suits you and works for your body? You could ask your health care provider for their recommendation, or find out what has worked for your friends. But researchers at Stanford University say there is a much more reliable source of nutritional advice: your genes. Their study, aimed at validating a new genetic test by Interleukin Genetics, Inc., involved over 100 overweight women who had participated in diet research published in 2007 that tested four diets (2 low-carb diets and 2 low-fat diets). After sending cheek swabs with their DNA to Interleukin, participants were classified as either "low-carb appropriate" or "low-fat appropriate."
When the researchers looked back at the original study's results, they found that those on diets that matched their genetic predisposition lost 2 to 3 times more weight than women on the "wrong" diets. "We were able to explain why some people were successful" and others were not, even though they followed the same diet, said Mindy Dopler Nelson, a nutritional biologist at Stanford and the study's lead author. The researchers also tested themselves. "It confirmed my suspicion," Nelson said of her result. "When I eat a lot of carbohydrates, I tend to put on weight."
Genetic testing was originally aimed at finding risk for diseases such as cancer, diabetes and Alzheimer's, but Interleukin hopes to expand its use to include lifestyle counselling-determining what type of diet or exercise is best. "Knowing your genotype for low-carb or low-fat diets could help you increase your weight-loss success," said Dr. Christopher Gardner, an Associate Professor of Medicine at Stanford and a co-author of the study. "It's not the end of the obesity epidemic, but we need every leg-up we can get." The new test is available in the market for a price of $149.
However, some scientists aren't buying into the findings, saying it's just another test being promoted without enough research to show it really works. "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 Centre of Excellence for Nutritional Genomics at the University of California, Davis. "I have serious reservations with this study and studies like it," Rodriguez agreed. "The idea that genetic variants in these genes can predict the likelihood for weight loss in such a small population, particularly since the tendency for weight loss is probably more behavioural than genetic, is simply hard to believe."
Dr. Robert Eckel, a former American Heart Association president and cardiologist at the University of Colorado-Denver, said while the research has appeal, it shows "nothing that should move the American public out to get their genome tested." He stresses that sticking with a diet is more important than what diet you choose. However, one of the study participants is a believer. Jacqueline Gardner, 55, of Evergreen, California went from 200 pounds at the start of the study to 185, but was back to 200 pounds two years later. "I now know why I gained it back," she said. The gene test showed she does not metabolize carbohydrates well. More recently, she has been on a high-protein diet and weighs 180. "I wish I had had a DNA test 10 years ago," she said.
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