THE MOST RECENT ROUND in the low-carb-vs.-low-fat food fight occurred last fall, with the publication of writer Gary Taubes’s 600-page tome, Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease. In painstaking detail, Taubes argues that the medical community got it terribly wrong in the 1950s, when experts started blaming dietary fat rather than carbohydrates for obesity, heart disease, cancer, and other health problems. Because of that colossal blunder, says Taubes, Americans have been getting fatter and fatter ever since.
According to Taubes, the man who played a central role in this drama—who “deserves the lion’s share of credit for convincing us that cholesterol levels predict heart disease and that dietary fat is a killer,” who first championed a low-fat diet—was none other than University of Minnesota physiologist Ancel Keys, one of the state’s most famous scientists.
Keys, who died in 2004 at 100, remains a legend among nutritionists. “He performed groundbreaking research that I knew about as a graduate student at Berkeley, long before I knew where Minnesota was,” says Dr. Mindy Kurzer, a professor of nutrition and director of the U’s Healthy Foods, Healthy Lives Institute. In 1961, Keys appeared on the cover of Time magazine, heralded as a national nutritional hero. He and his wife became the authors of a bestselling cookbook, Eat Well and Stay Well, which touted what soon became known as the Mediterranean diet. “People still idolize him here,” Kurzer says. “Around the time of his 100th birthday, there was a huge symposium to honor him. Hundreds of people came.”
Certainly, American food habits would have been a lot different without Keys. “The belief in the benefits of a low-fat diet would never have gotten as far as it did” without him, Taubes said in a recent interview. But did Keys’s success in spreading that belief end up leading us down a path to misery?
BORN IN COLORADO and raised in California (where, as a toddler, he survived the San Francisco earthquake of 1906), Keys came to Minnesota in 1937 after receiving two doctorate degrees, one in oceanography and biology, from the Scripps Institute in California, and the other in physiology, from King’s College, Cambridge. At the U, he commandeered a cramped space under Gate 27 of the old Memorial Stadium and launched what quickly became a world-renowned research laboratory, running the lab until his retirement in 1972.
During World War II, Keys became famous for developing the K ration, the ready-to-eat meal used by combat troops. (He claimed the K stood for Keys.) Later in the war, as reports began surfacing of millions of starving Europeans, Keys conducted a comprehensive study on human starvation, with 36 young, male conscientious objectors as his subjects. That study remains the fullest account of the physiological effects of starvation on the human body and mind.
It was his post-war research on diet and heart disease, however, that brought Keys fame and fortune. It also led to the “low-fat dogma,” as Taubes calls it, that has become the mantra of the government and the medical establishment.
Keys hypothesized that heart disease was mostly a nutritional disorder, linked directly to the amount of fat in the diet: High-fat foods raised cholesterol levels in the blood, which, in turn, increased the risk of clogged arteries and heart disease. According to Henry Blackburn, his longtime collaborator, Keys developed this idea by reading the obituaries in local newspapers. He noticed that presumably well-fed Minnesota executives were dropping dead in their fifties, while in postwar Europe, where food—especially meat—was in short supply, the rate of heart attacks had plunged.
From the start, Keys’s hypothesis was disputed, most notably at a 1955 meeting of the World Health Organization. Keys, a man of extreme confidence, had expected his ideas to be immediately accepted, but instead he found himself challenged by Sir George Pickering, one of Britain’s leading physicians and an internationally known expert on heart disease. “Keys slunk out of that meeting with his tail between his legs,” says Blackburn. “I’m convinced that that’s when he decided to do the Seven Countries Study, and to do it right.”
In response, Keys decided to perform what became known as the Seven Country study. Began in 1958 and ended in 1970, the study monitored almost 13,000 men aged 40 to 59. The subjects were from 16 mostly rural areas in seven countries—Yugoslavia, Italy, Greece, Finland, the Netherlands, Japan, and the United States. Keys and his team of researchers measured each enrollee’s cholesterol levels, blood pressure, body weight, and more. And, of course, they analyzed the men’s diets.
Keys claimed that the findings from this ambitious undertaking (considered the first large-scale prospective study of heart disease) vindicated his theory about dietary fat and heart disease. In places where fat was a major component of every meal, such as in the United States and Finland, blood cholesterol levels were the highest—and so were deaths from heart attacks, he reported. But in places where people dined mostly on bread, pasta, fresh fruits, vegetables, and olive oil (areas around the Mediterranean, for example), blood cholesterol was low and heart attacks were rare. Data in hand, Keys took his findings public, advocating that Americans limit their fat consumption to roughly 30 percent of total daily calories. (At first, he lumped all dietary fat together, but later he begrudgingly agreed that not all fats were created equal: Research indicated that saturated fats raised cholesterol, while monounsaturated fats lowered it.)
FROM THE OPENING PAGES of his book, Taubes, a correspondent for Science magazine, paints Keys as an agenda-driven scientist who pushed Americans toward low-fat diets despite a lack of credible facts to back up his assertions. He rips Keys’s research, saying that the Minnesota physiologist tended to dismiss any findings that didn’t support his hypothesis. “The fact, for instance, that Japanese men who lived in Japan had low blood-cholesterol levels and low levels of heart disease was taken as a confirmation of Keys’s hypothesis, as was the fact that Japanese men in California had higher cholesterol levels and higher rates of heart disease,” writes Taubes. But when research also showed that even Japanese men in California with low cholesterol were more likely to have heart disease than their counterparts in Japan, Keys pronounced the findings irrelevant. The truth, Taubes says, conflicted with Keys’s ideas.
Like initial critics of the Seven Countries Study, Taubes points out that if Keys had surveyed more countries, his results would have been startlingly different. Had he analyzed data from the 22 countries for which information was available at the time, for instance, he would have discovered that “the apparent link between fat and heart disease vanished,” notes Taubes. (Thus, the “French Paradox”—the observation that the French have a low incidence of heart disease despite dining regularly on such saturated-fat delights as buttery croissants and beef bourguignon—isn’t a paradox at all, says Taubes.)
Perhaps the most damning charge in Taubes’s book is that after Keys maneuvered to get himself and an ally on an influential American Heart Association (AHA) committee in 1961, the organization suddenly did an about-face and issued a report calling for Americans to start shunning saturated fat to lower their risk of heart disease. Just four years earlier, the AHA had snubbed Keys by claiming the evidence for such a recommendation was far too flimsy.
So did Keys mislead us by preaching the evils of saturated fat? Are carbohydrates the true trickster behind the recent obesity epidemic and its associated medical problems? There is no question that Taubes thinks so. The most compelling current research, he says, suggests that by raising the levels of insulin in our blood, carbohydrate-rich foods, like potatoes, white bread, sugar, and pasta encourage our bodies to store ever-expanding slabs of fat. All of which may sound eerily familiar (paging Dr. Atkins…).
But don’t stock your freezer with marbled meat just yet. “Food is incredibly complex,” says David Jacobs, PhD, a professor of epidemiology at the U of M. Focusing on one nutrient, such as fat or carbohydrates, is too limiting, he argues, to fully understand all the intricate and interacting factors in foods that affect human health.
Jacobs believes both Keys and Taubes have oversimplified things. “I grew up academically with Ancel Keys and his idea that saturated fat is bad because it raises cholesterol,” says Jacobs. “That logic is interesting, but I think there’s more going on with heart disease than just cholesterol.” But he also disagrees with Taubes’s most controversial claims: that different kinds of calories have varying effects on the hormones that control fat accumulation; and that a calorie of fat is less fattening than a calorie of sugar. Says Jacobs, “I think a calorie is a calorie.”
For now, it may be best to stay tuned and stock up on vegetables. That’s one piece of advice both sides of the diet wars can agree on.
Susan Perry writes about health and medicine for Minnesota Monthly.