(credit: Allan Foster / Flickr) In a 609-person, year-long study, dieters lost an average of about 12 pounds—regardless of whether they were trying to stick to a low-fat or a low-carb diet and regardless of whether they carried genetic variations linked to success on one of those diets. The lackluster finding, published by Stanford researchers this week in JAMA, knocks back hopes that we’re at the point of harnessing genetic information to tighten our waistlines.