A low-carbohydrate or Atkins-style diet is more effective for weight loss and improved cholesterol levels than a low-fat, low-cholesterol diet, according a study reported in the May 18 issue of the Annals of Internal Medicine.

"This (low-carb) diet can be quite powerful," said lead researcher Will Yancy, M.D., an assistant professor of medicine at Duke University Medical Center.

The study is the first randomized, controlled trial of the popular Atkins low-carbohydrate diet. Besides losing an average of 26 pounds versus an average of 14 pounds by low-fat dieters, Atkins dieters lost more body fat and ended up with better triglyceride and good cholesterol (HDL) levels than low-fat dieters.

Despite reporting more adverse physical effects, such as constipation and headaches, the low-carb diet group also had fewer dropouts than the low-fat diet group.

The study, funded by the Robert C. Atkins Foundation, builds on earlier results by the Duke University Medical Center researchers showing a low-carbohydrate diet can lead to weight loss.

Despite the considerable weight loss experienced by the low-carbohydrate dieters, Yancy does not recommend an Atkins-style plan for patients attempting to lose weight for the first time, noting that a longer study is needed. Instead, he cautioned that the diet could present certain health risks, such as elevations in LDL cholesterol levels, bone loss or kidney stones.

Yancy also urged people with diabetes and high blood pressure to not start an Atkins-style diet without close medical supervision since a low-carbohydrate diet affects hydration and blood sugar levels.

The study involved 120 people randomly assigned to either the low-carbohydrate, high-protein diet or the low-fat, low-cholesterol, low-calorie diet. All were between 18 and 65 years old and in generally good health with a body mass index (BMI) that indicated obesity and a total cholesterol level of more than 200 mg/dL.

The low-carbohydrate group was permitted daily unlimited amounts of animal foods and eggs as well as four ounces of hard cheese, two cups of salad vegetables and one cup of low-carbohydrate vegetables such as broccoli, cauliflower or squash. They also received daily nutritional supplements recommended by Atkins such as a multivitamin, essential oils, a diet formulation and chromium picolinate. There were no restrictions on total calories, but carbohydrates were kept below 20 grams per day at the start of the diet.

The low-fat, low-cholesterol, low-calorie group followed a diet consisting of less than 30 percent of daily calories from fat, less than 10 percent of calories from saturated fat and less than 300 milligrams of cholesterol daily. They were also advised to cut back on calories. The recommended daily calorie level was 500 to 1,000 calories less than the calories that the participants needed to maintain their current weight.

Study participants were encouraged to exercise 30 minutes at least three times per week, but no formal exercise program was provided.

Yancy and co-researcher Eric Westman, M.D., are currently testing whether a low-carbohydrate diet can help diabetics control their blood sugar levels.

Other sources: Duke University Medical Center