Recommendations about dietary fat have shifted over the last two decades. From the 1970s through the 1990s, nutrition researchers emphasized eating a low-fat diet. This was largely because of concerns about saturated fats. Saturated fat that’s in the bloodstream raises the levels of LDL cholesterol—the “bad” cholesterol. This in turn raises the risk of heart disease.
But when people started following low-fat diets, they didn’t only cut saturated fats. In many cases, they replaced healthy unsaturated fats with processed carbohydrates. Many adults would consume fat-free foods, like cookies, crackers, and ice cream, made with refined grains and sugar. As scientists have learned, those replacement calories matter. Studies have shown that replacing saturated fat with unsaturated fat reduces the risk of heart disease. However, replacing saturated fat with simple carbohydrates, such as added sugar and white bread, does not.
Experts note that there’s still a misconception that eating fat—any kind of fat—is bad. That it will lead to heart attacks, or weight gain, but this isn’t true. People should be encouraged to eat healthy fats.