DNA testing won't guide dieters to the weight-loss regimen most likely to work for them, scientists reported on Tuesday. From a report: Despite some earlier studies claiming that genetic variants predict whether someone has a better chance of shedding pounds on a low-carbohydrate or a low-fat diet, and despite a growing industry premised on that notion, the most rigorous study so far found no difference in weight loss between overweight people on diets that "matched" their genotype and those on diets that didn't. The findings make it less likely that genetics might explain why only some people manage to lose weight on a low-carb diet like Atkins and why others succeed with a low-fat one (even though the vast majority of dieters don't keep off whatever pounds they lose). Unlike cancer treatments, diets can't be matched to genotype, the new study shows. The results underline "how, for most people, knowing genetic risk information doesn't have a big impact," said Timothy Caulfield, of the University of Alberta, a critic of quackery.