More than 80 clinical studies have demonstrated the effectiveness of the Atkins diet. One such trial, conducted at Stanford University Medical School in 2007, found that after one year, people on the Atkins diet had list. 4.7kg (10.4lbs) - more than those on the Ornish, Zone, or LEARN diets. A similar study published the following year reported 8.3kg (18.3lbs) lost under Atkins, which again beat out the Zone and Ornish diets. A 2006 study from the UK found that while it was not noticeably better than other diet options examined, the Atkins diet did result in significant loss of weight and body fat over a 6-month period, and produced faster weight loss during the first 4 weeks than other weight loss plans. Even studies that have found Atkins to be less effective than other diets still report notable weight loss and improved health after several months on the Atkins plan.
A study from 2004 looked at low-carb diets more generally. 132 obese adults had been assigned to either a "conventional" diet that only involved calorie restriction, or a low-carb diet. After being on these diets for a full year, mean weight loss for the low-carb group was 5.1kg (11.2lbs) compared to 3.1kg (6.8lbs) for the low-calorie group. The low-carb diet also led to reductions in LDL cholesterol and was better than the low-calorie diet for diabetic participants.