A study published in the Journal of American Medicaal Association (JAMA) put women who were overweight and premenopausal on four different diets: Atkins (low carbohydrate), Ornish (low fat), Zone (a balance of 40% carbohydrates, 30% fat, and 30% protein), and LEARN (a low-fat, high-carb eating plan recommended by the federal government).

The women were given diet books, attended an eight-week nutrition class, and then largely left alone over the course of the study, except for checkups at two, six and 12 months. The women prepared their own meals and bought their own food.

The Atkins’ diet in terms of weight loss as well as risk factors.

Although some women in each of the four groups lost as many as 30 pounds, the average participant lost far less. The Atkins dieters lost, on average, 10.4 pounds, while the women in the control group lost 5.7 pounds. The Ornish dieters lost a little under five pounds, while the Zone dieters lost the least, with an average drop of 3.5 pounds.

Some nutrition experts have worried that the Atkins diet, high in animal fat and protein, could raise cholesterol and blood pressure, but their concerns were not borne out in this study and some other recent studies. The Atkins dieters’ “good cholesterol” levels rose compared with the other diet groups and blood pressure declined compared with some of the other diet groups.

The researchers noted that the weight lost by the Atkins dieters was only statistically significant when compared with the Zone dieters. Given that fewer than 80 women were in each group, the differences in weight loss between the Atkins and the Ornish and control-group dieters could have happened by chance. There were no statistically significant differences between the Ornish, Zone and control groups.