Stop Worrying About Total Fat
Unfounded fat fears even affect the Nutrition Facts label.
Two of the nation’s leading nutrition experts have some advice for the federal government: Stop worrying about total fat. Nutrition research has shown that the emphasis on restricting total fat intake is outdated, yet these limits affect everything from Nutrition Facts labels to school lunches to supermarket products. In recent opinion pieces in JAMA and the New York Times, Dariush Mozaffarian, MD, DrPH, and David S. Ludwig, MD, PhD, argue, “It’s long past time for us to exonerate dietary fat.”
Dr. Mozaffarian is dean of Tufts’ Friedman School of Nutrition Science and Policy and editor-in-chief of the Tufts Health and Nutrition Letter. Dr. Ludwig is on the staff of Boston Children’s Hospital and directs the New Balance Foundation Obesity Prevention Center.
However the federal government responds to this call for change—in the upcoming 2015 US Dietary Guidelines, revised nutrition labeling and other policies—you can catch up with the latest nutrition science in your own grocery shopping and food preparation right now. If, like Uncle Sam, you’re still worrying about the total fat numbers and calories from fat on the Nutrition Facts panel, it’s time to take a more nuanced view. If you’re avoiding foods high in healthy unsaturated fats, you need to rethink your fear of fats.
DATED NUMBERS: The 2015 report of the Dietary Guidelines Advisory Committee (DGAC) drew headlines for overturning most concerns about consumption of dietary cholesterol, as in eggs (see the May newsletter). Tufts faculty members Alice H. Lichtenstein, DSc, and Miriam Nelson, PhD, served on the committee, and Lichtenstein was vice-chair. As Dr. Mozaffarian and Dr. Ludwig point out, however, “A less noticed, but more important, change was the absence of an upper limit on total fat consumption.”
Noting that reducing total fat intake by substituting carbohydrates does not reduce cardiovascular risk, the DGAC concluded, “Dietary advice should put the emphasis on optimizing types of dietary fat and not reducing total fat.”
That recommendation, if reflected in the final guidelines due later this year, would reverse 35 years of nutrition policy. In 1980, the federal Dietary Guidelines first recommended limiting dietary fat to less than 30% of calories. Since one gram of fat—regardless of the type of fat—contains about 9 calories, in a 2,000-calorie daily diet that advice translated to a maximum of 65 grams of fat per day. The 1980 recommendation was revised in the 2005 guidelines to a range of 20% to 35% of calories from total fat. But the percentages used in the Nutrition Facts panel continue to be based on the 1980 recommendation of 30% or 65 grams.
SUBSTITUTING CARBS: Fat is a concentrated source of calories—that 9 calories per gram of fat compares to 4 per gram of protein or carbohydrate. So limiting fat intake seemed like a sound strategy for preventing obesity. As the Times op-ed recounts, "By the mid-1990s, a flood of low-fat products entered the food supply: nonfat salad dressing, baked potato chips, low-fat sweetened milk and yogurt and low-fat processed turkey and bologna. Take fat-free Snackwell’s cookies. In 1994, only two years after being introduced, Snackwell’s skyrocketed to become America’s No. 1 cookie, displacing Oreos, a favorite for more than 80 years."
In place of fat, Americans were advised to eat carbohydrates, which were positioned as the foundation of a healthy diet. In 1992, the USDA’s famous “food pyramid” recommended up to 11 daily servings of bread, cereal, rice and pasta. (By contrast, the current MyPlate nutrition icon recommends women consume five to six ounces or ounce-equivalents of grains, depending on their age, and six to eight for men. At least half those servings should be whole grains.)
Replacing fats with carbohydrates, especially refined sources as in packaged foods, backfired as an anti-obesity strategy. Between 1980 and 2000, obesity rates among US adults doubled.
In the thinking behind the 1980 total-fat limit, saturated fat was also linked to unhealthy cholesterol levels. “But the campaign against saturated fat quickly generalized to include all dietary fat,” Dr. Mozaffarian and Dr. Ludwig write in JAMA. “Moreover, a global limit on total fat inevitably lowers intake of unsaturated fats, among which nuts, vegetable oils and fish are particularly helpful.”