If you read today’s news about low-fat diets, you might be tempted to start choking down lard by the bucketful (we wouldn’t recommend it, but to each his own). On Tuesday afternoon, scientists with the National Institutes of Health announced results from “one of the largest studies of its kind ever undertaken in the United States,” a $415 million, 15-year research behemoth. All of the study subjects were post-menopausal women, half of whom were instructed to eat a low-fat diet with an increased intake of fruits, vegetables, and grains. The results are striking: “In this study, a low-fat dietary pattern intervention did not reduce the risk of colorectal cancer in postmenopausal women during 8.1 years of follow-up.””[A] low-fat dietary pattern did not result in a statistically significant reduction in invasive breast cancer risk over an 8.1-year average follow-up period.””[A] dietary intervention that reduced total fat intake and increased intakes of vegetables, fruits, and grains did not significantly reduce the risk of CHD [coronary heart disease], stroke, or CVD [cardiovascular disease] in postmenopausal women.”
Dr. Jules Hirsch, a physician who’s spent his career studying diets and health, chimed in on this theme of scientific humility, telling The New York Times that these studies “should put a stop to this era of thinking that we have all the information we need to change the whole national diet and make everybody healthy.” Amen, doc. Since the conventional wisdom on nutrition gets overturned pretty regularly, it becomes very difficult to justify any “national diet” plan that includes sin taxes and obesity lawsuits.
Dr. Walter Willett — a Harvard prof who, we must admit, has spread his share of fat fads in the past — called these results “the end of the low-fat era.” That may be true. But we’ll take these findings in stride, preferring this observation from UC Berkeley statistics professor David Freedman: “We, the scientific community, tend to go off the deep end giving dietary advice based on pretty flimsy evidence.”