One of the longest trials to pit low-fat diets against Atkins-style diets found that participants lost the same amount of weight after two years, regardless of which diet they were on, though the Atkins dieters had greater increases in HDL, or “good” cholesterol. Previous studies have shown mixed results.

The clinical trial randomly assigned 307 obese adults from three sites to either a low-calorie, low-fat diet or an Atkins-style low-carbohydrate regimen. Both groups of dieters participated in intensive behavior modification classes as well. After two years, dieters on both plans lost an average of 15 pounds, according to the study, in the Aug. 3 Annals of Internal Medicine.

No matter what diet plan they followed, dieters saw improvements in heart disease risk factors, including lower triglycerides and lower LDL, or ‘bad’ cholesterol. Low-carb dieters had greater increases in HDL, the good cholesterol, but also experienced more side effects at the beginning, including bad breath, constipation, hair loss and dry mouth.

Dr. Gary Foster, the paper’s lead author and director of the obesity center at Temple University, said, “As little as a 4 percent weight loss has been found to prevent development of Type 2 diabetes.”