In the 1980s and 1990s, Americans were told that eating less fat would reduce risk for cardiovascular disease and obesity. Why didn’t it work? Essentially, reducing total fat led to intake of more refined carbohydrates and less healthy fats, and both of these changes had negative health impacts.
Evolving Guidelines: Dietary advice on fat intake has evolved over the years. Based on strong evidence that diets high in saturated fats and cholesterol were associated with high blood cholesterol levels and a greater risk of heart attack, the 1980 U.S. Dietary Guidelines recommended Americans “avoid too much fat, saturated fat, and cholesterol.” The 1990 Dietary Guidelines added risk for obesity to the list of reasons to cut back on fats. (Since a gram of fat has more than twice the calories of a gram of protein or carbohydrate, reducing fat intake is the fastest way to reduce calorie intake.) But, soon thereafter, data began to emerge that low-fat diets were not having the expected results. “The 2000 Dietary Guidelines Advisory Committee noted the adverse effects of low-fat diets, and for the first time since their inception changed the guidance from low fat to moderate fat,” says Alice H. Lichtenstein, DSc, a member of that committee who is now a senior scientist at Tufts’ HNRCA and executive editor of Tufts Health & Nutrition Letter. From 2000 on, the Dietary Guidelines for Americans (DGA) recommended consuming a diet moderate in total fat that keeps saturated fat intake to under 10 percent of calories. The 2015 DGA emphasizes consuming foods rich in polyunsaturated fat. Some scientists feel that even this moderate fat restriction goes too far. Dariush Mozaffarian, MD, DrPH, dean of Tufts’ Friedman School of Nutrition Science and Policy and editor-in-chief of Tufts Health & Nutrition Letter sites evidence that a higher proportion of calories from fat is not harmful for either cardiovascular disease (CVD) or obesity, and in fact can lower risk if healthy (poly- and mono-unsaturated) fats replace refined starches and sugars. Continue reading