By:
Sharon Palmer, RD
“Eat a low fat diet.”
That was the public health message 30 years ago—which turned out to be dead wrong and set off a national fat phobia.
Some of the country’s leading nutrition experts discussed this decades-old debate about optimal fat intake at the American Dietetic Association’s Food & Nutrition (DGAC) Conference. Walter Willet, M.D., Ph.D., chairman of the nutrition department at the Harvard School of Public Health, reported at the conference, “Data in the 1980s found that total fat and coronary heart disease had no co-relationship; it was the type of fat—not total fat—in the diet that was important.” At that time, research did not link low fat diets with energy balance and a lowered risk of type 2 diabetes or breast and colon cancer, either.
But that didn’t stop health experts from promoting low-fat diets for all.
Low fat mania
Alice Lichtenstein, D.Sc., director of the cardiovascular health laboratory at Tufts University, says that three decades ago advice to lower fat came out of an over-simplification of recommendations; instead of emphasizing replacing saturated fats with unsaturated fats, the advice was, simply, “lower fat intake.”
Soon the “eating fat makes you fat” myth took hold, and the food industry created “low fat” everything, from cookies to snack foods. The manufacturers skimmed off part of the fat in their formulations and dumped in refined carbs like white flour and sugar to fill in the flavor gaps. People started reaching for the low fat version of foods, patting themselves on the back for making a “healthy” decision. And since the low fat food was “healthy,” why not eat the whole box?
Fat revisited
Let’s take a fresh look at the types of fat and cholesterol and how they impact health.
Total fat: Dietary fats are a class of nutrients that include specific fatty acids, such as polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs.) Many foods contain a combination of different kinds of fats. While it’s well established that you should no longer obsess over lowering total fat, consider this: Fat contains nine calories per gram (carbs and protein contain four calories per gram), so they are a key factor in maintaining calorie and weight balance. A healthy weight is one of the most important ways to prevent chronic disease.
Though science reveals no perfect formula of fat, carbs and protein that leads to the most successful weight loss, there is evidence that dietary patterns relatively low in calorie density—high in vegetables, fruit, and total fiber and relatively low in total fat and added sugars—are associated with healthy body weights. The Dietary Guidelines Advisory Committee (DGAC,) a panel of experts tasked to review the database of science in order to devise guidelines for eating, recommends a total fat intake of 20 to 35 percent of calories for adults, which adds up to 44 to 78 grams (g) for the average person—with further emphasis on the types of fats consumed within this range.
Saturated fat: Saturated fats found in animal fats and tropical oils (palm, coconut) have consistently been painted as the “bad guy” of the fat world, but recently that idea has encountered argument. A meta-analysis published in the January 2010 American Journal of Clinical Nutrition showed no significant evidence that saturated fat is associated with increased risk of coronary heart disease (CHD) or cardiovascular disease (CVD.)
Dariush Mozaffarian, M.D., Ph.D., associate professor at the Harvard School of Public Health, says, “If you replace saturated fats with PUFAs you see an overall benefit. If you replace saturated fats with processed carbs, the risk increases significantly. It’s not useful to focus on saturated fats any longer.”