Dietary fat — long demonized by nutrition experts, federal authorities, and the food industry — may not be as bad for your health as sugar, a new evaluation of medical evidence suggests.

In fact, efforts made over the last three decades to convince Americans to eat more low-fat foods — which are often laden with sugar and carbs — have fueled the nation’s growing obesity crisis, the researchers say. What’s more, sugar consumption plays greater role in heart disease than saturated fat, they have concluded.

"After a thorough analysis of the evidence it seems appropriate to recommend dietary guidelines shift focus away from recommendations to reduce saturated fat and towards recommendations to avoid added sugars," said lead researcher Dr. James J. DiNicolantonio, a cardiovascular expert with Saint Luke's Mid America Heart Institute in Kansas City, Mo.

"Most importantly recommendations should support the eating of whole foods whenever possible and the avoidance of ultra-processed food."

Atherosclerotic coronary heart disease (CHD) causes one in every six deaths in the United States and is leading cause of death in the developed world. But healthcare professionals’ decades-long efforts to targeting CHD by recommending limitations on saturated fats has actually made the problem worse, the new study suggests.

In an article published in the journal Progress in Cardiovascular Diseases, Dr. DiNicolantonio and colleagues note the notion that dietary saturated fats is the principal promoter of high cholesterol and heart disease stemmed from research in the 1950's by an American scientist Ancel Keys. The theory was embraced by the American Heart Association and the federal government in the 1960s and 70s and drove an explosion in the development and sales low-fat foods — including skim milk, margarine, and other products.

Yet at the same time, a British physiologist John Yudkin argued that sugar intake was more closely related to incidence of and mortality from CHD.

Dr. DiNicolantonio and colleagues evaluated the evidence to date linking saturated fats and sugars to CHD, considering basic science, epidemiology, and clinical trial data. They concluded that sugar consumption, particularly in the form of refined added sugars, are a much greater contributor to CHD than saturated fats.

"While the original studies upon which the longstanding guidelines were based were largely observational, we now have more than a half century of data as well as increased understanding of how nutrition impacts the body and specifically coronary heart disease," said Dr. DiNicolantonio.

In fact, research shows certain saturated fatty acids may actually confer measurable heart benefits and boost levels of HDL “good” cholesterol.

At the same time, replacing saturated fats with carbohydrates — particularly refined carbs like sugar — can lower HDL, while also causing dangerous blood fats known as triglycerides to rise.