Spending time on a low-fat diet may result in a loss of weight, but it probably isn’t going to do much of anything for your heart health or cholesterol levels. Interpreting results from one of the largest studies on women every conducted, the Women’s Health Initiative, brought surprising results, although not without controversy.

According to a published article in the April issue of the American Journal of Clinical Nutrition, low-fat diets will not hurt your heart or lower your cholesterol, although those who lowered their consumption of harmful fats—trans fat and saturated fat—did have a lower incidence of heart disease.

In the early 1990s, the Women’s Health Initiative (WHI) was established by the National Health Institute and embarked on a long-term study of women’s health issues. The fifteen-year study was designed to address the most common causes of death, disability and impaired quality of life in postmenopausal women, and to this day it is the one of the largest preventative studies ever conducted. One component of the study was a Dietary Modification Trial that provided one group of women intensive training and education on eating a low-fat diet and compared their health with women a control group who didn’t modify their eating habits.

Study author Barbara V. Howard, a professor of medicine at Georgetown University, said: “This diet did not raise triglycerides and didn’t lower HDL cholesterol…[but] eating a low-fat diet might make it easier to lose weight, which is important because of the current American epidemic of obesity.”

Critics of the study, such as Jeff Volek, associate professor of kinesiology at the University of Connecticut, are concerned about conclusions being made from this study. According to a statement he made to BusinessWeek: “It’s difficult to make any firm conclusions from a study like Women’s Health Initiative because, after years of being prescribed a diet, very few people are actually on the diet.” Self-reports of food intake “are notoriously inaccurate…even though the number of subjects is large, the noise is even greater so that these studies contribute very little to actual knowledge on the interaction of diet and health.”