The low-fat diet has been around for a while, yet many consider it just another in a long line of fad diets. This is far from the truth. A new study supports the idea that making modest changes to how much fat you eat brings many long-term benefits.

Researchers at Fred Hutchinson Cancer Research Center used information gathered from the Dietary Modification Trial, a study that began in 1993. It involved almost 49,000 postmenopausal women in the U.S., and its purpose was to see if a low-fat diet would decrease the risk of breast and colorectal cancers, as well as coronary heart disease.

“What should I be eating?” This study provides support for the long-term benefits of a low-fat diet.

During the first year of the study, the participating women were taught concepts that combined nutrition and behavior by trained nutritionists, and they made intentional dietary changes. The concepts were reinforced four times a year for almost ten years.

Nine years into the study, it appeared that the low-fat diet, which included adequate amounts of fruits, vegetables and grains, had no substantial benefit for these conditions, but after nearly 20 years, significant benefits began to emerge. There was a 15 to 35 percent decrease in deaths from all causes after breast cancer, a 13 to 25 percent decrease in cases of insulin-dependent diabetes, and a 15 to 30 percent decrease in coronary heart disease in 23,000 women who had no prior heart disease or high blood pressure.

Ross Prentice, PhD, one of the original researchers with the Dietary Modification Trial, explained: “The latest results support the role of nutrition in overall health, and indicate that low-fat diets rich in fruits, vegetables and grains have health benefits without any observed adverse effects.”

Other studies have looked at the connection between diet, cancer and other diseases, but this study was designed to be a long-term, randomized, controlled trial – the gold standard for clinical research.

For people who just want to know, “What should I be eating?” and are overwhelmed by the ever-increasing number of new diets and nutrition fads, this study provides scientific support to the long-term benefits of eating a low-fat diet, according to Garnet Anderson, a co-author of the study.

A low-fat diet is largely what is also known as a Mediterranean diet. It includes plenty of plant foods like whole grains, fruits and vegetables, and a moderate amount of animal-based foods, such as lean meats and reduced-fat dairy foods. Cooking methods such as trimming the visible fat from meat and baking, broiling or grilling meat rather than frying it also contribute to a low-fat diet.

The study was published in the Journal of Nutrition.