Dietary Fat: Friend or Foe?

Abstract

For many years, low-fat diets were the cornerstone of public health and clinical guidelines for preventing and treating obesity. The US Senate Select Committee on Nutrition released the first national guidelines in 1977. At that time, Dietary Goals for the United States included recommendations to “increase carbohydrate consumption to between 55% and 60% of the energy (caloric) intake” and “reduce fat consumption from over 40% down to 30% of energy intake.” These recommendations were based, in part, on the idea that consuming fat promotes obesity because fat is the most concentrated source of energy in the diet. Despite limited data, the recommendation to reduce dietary fat was underscored in 1984 by an expert panel at the NIH Consensus Development Conference on Lowering Blood Cholesterol to Prevent Heart Disease , and again in 1987 by the National Cholesterol Education Program (NCEP). Dietary fat was viewed as a “foe” to good health from 1984 through the 1990s. Currently, Dietary Guidelines for Americans 2015–2020 (Eighth Edition) focus on eating patterns, and associated food and nutrient profiles, rather than on nutrient intakes. While there is no explicit limit on total fat intake, the Guidelines continue to advocate <10% of calories from saturated fat, consistent with recommendations in developed countries internationally. Interestingly, the daily nutritional goals and healthy eating examples, appended to the Guidelines , reflect an upper limit for total fat of 35% of calories, suggesting continued reluctance to promote higher fat consumption. During the era of low-fat diets, the food industry replaced fat with refined carbohydrate in many products, such that public health messages had unintended consequences. Over the past two decades, the prudence of low-fat diets has come under intense scrutiny, in light of emerging data from prospective cohort studies and randomized controlled trials showing adverse effects of refined carbohydrate on risk …