The End of the Low-Fat Era?

The year was 1977. The US Senate Select Committee on Nutrition and Human Needs, led by Senator George McGovern, issued the first Dietary Goals for Americans, thereby marking the beginning of the low-fat era of dietary nutrition, arguably the most misguided period of government-led nutrition ever. After 38 years, however, the low-fat era might officially end later this year.

The Dietary Goals evolved into the Department of Health and Human Services’ (HHS) and Department of Agriculture’s (USDA) Dietary Guidelines for Americans, later represented as the Food Pyramid and, currently, as MyPlate. The Guidelines’ dominant theme has been that calories consumed should equal calories expended. And since fat has 9 calories per gram, compared to only 4 for both carbohydrates and protein, fat became typecast as the “bad guy” nutrient.

Furthermore, since saturated fat and dietary cholesterol have been thought to promote cardiovascular disease, the Guidelines have recommended restricting fat to less than 30% (revised to 35% in 2005) of total calories. Consequently, carbohydrates, particularly refined carbohydrates and added sugars, came to replace healthy fats in Americans’ diets.

USDA and HHS update the Guidelines once every five years and the next revision is forthcoming later this year. Historically, the Guidelines echo the Dietary Guidelines Advisory Committee (DGAC) report, written by appointed scientists who systematically review the scientific literature on nutrition. The current DGAC report, published earlier this year, features two monumental deviations from the current Guidelines.

First, as we previously reported, the DGAC no longer considers dietary cholesterol to be a “nutrient of concern.”¹ Previously, they recommended limiting cholesterol to 300 mg/day, but now acknowledge, “available evidence shows no appreciable relationship between consumption of dietary cholesterol and serum cholesterol.”

Second, the DGAC recommends removing upper limits on total fat consumption with respect to total calories. “In low fat diets,” they write, “fats are often replaced with refined carbohydrates and this is of particular concern because such diets are generally associated with dyslipidemia.”² Reducing total fat (replacing total fat with overall carbohydrates), they conclude, “does not lower cardiovascular disease risk.”

So what does all this mean? If USDA and HHS follow the DGAC’s recommendations, the low-fat era will finally end and, going forward, Americans will have more scientifically accurate information about fat and will likely embrace healthful, fatty foods more readily.

Calling all nutrition advocates

The DGAC recommendations are clear, but in making their final decision, the USDA and HHS also consider comments from the public, academics, advocacy groups, and industry. As such, two prominent scientists, Dr. David Ludwig and Dr. Dariush Mozaffarian, recently penned an article for the Journal of the American Medical Association in which they strongly endorsed lifting the total fat limits.³

Their article follows-up on a similar article they co-authored in 2010 about the previous Dietary Guidelines update. In their 2010 article, they recommended moving away from a nutrient-metrics approach, whereby specific nutrient targets are defined, and toward an approach emphasizing specific, healthy foods. They noted that the proportion of total energy from fat “appears largely unrelated to risk of cardiovascular disease, cancer, diabetes, or obesity” and that saturated fat “has little relation to heart disease within most prevailing dietary patterns.”⁴

We recently caught up with Dr. Mozaffarian to ask him about this extremely important story.

Q: What are your impressions about the progress made since your 2010 article with Dr. Ludwig? Are we moving in the right direction?

A: The 2015 DGAC report has made great strides in the right direction, with its major new focus on healthful, food-based, diet patterns. Now we must wait to see what the USDA and HHS do with this information in the final Guidelines—boldly move toward this modern evidence, or sit back and return to old conventions.

Assuming the USDA drops its limits on total fat consumption, how impactful do you think this could be?

This could have tremendous positive impact, especially if mirrored in other national policies e.g. food labeling, school lunch, feeding programs, and so on. Consumers and companies would be unshackled to allow focus on increasing healthy foods, including those higher in fat, and on reducing refined grains and sugars.

Would you care to comment on the Paleo diet from a nutritional perspective?

The main benefits of Paleo are recognizing the harms of refined grains, starches, and sugars, which dominate the food supply; and the (potential) focus on fruits, vegetables, nuts, and fish. But, if ‘Paleo’ leads one to high-meat diets, few benefits will be gained.

Dr. Mozaffarian makes a valid point. One of the largest misconceptions surrounding Paleo diets and lifestyles is that it promotes high-meat consumption without balance from other food groups. Dr. Cordain among the many other thought leaders in the scientific and lay communities continue to debunk this misconception. A real Paleo diet is a high-vegetable diet with moderate amounts of animal protein, including lean meat and fish high in omega-3, plus animal and vegetable sources of fat.

In our interview with Dr. Mozaffarian, he also noted that some vegetable oils “are extremely healthy, but are shunned by many Paleo aficionados.” While we respectfully disagree about the health impact of high-omega-6 vegetable oils, we strongly agree that proportional upper limits on total fat must be removed from the US Dietary Guidelines.

For nearly four decades, the US government has promoted high-carbohydrate, low-fat diets. Incidentally, a recent systematic review of the randomized controlled trials available to McGovern’s Committee back in 1977 determined there was no scientific basis for their restrictions on fat.[5] In other words, the low-fat era never should have happened. And with the 2015 Dietary Guidelines update, it should finally end.