In the case of heart disease, Reaven says that high blood concentrations of insulin and glucose can damage the endothelium that lines coronary arteries and set the stage for the formation of plaques. “A big problem is the lack of drugs to treat this problem,” he adds. “A lot of doctors’ education comes from drug companies. They know about cholesterol because everyone is pushing their statin. They know about hypertension because there are multiple hypertensive drugs. But they know a lot less about insulin resistance and its consequences, and that’s unfortunate.”

Syndrome X, also known as metabolic syndrome or insulin-resistance syndrome, is largely unknown to the public as well. While many people avoid cholesterol and fat-laden foods, few understand the threat posed by carbohydrate excess. That needs to change, says Willett. “Cholesterol is relevant, but the danger is overblown,” he says. “Syndrome X is the global public-health problem of the 21st century. Almost certainly the vast majority of Americans have a higher degree of insulin resistance than is optimal.”

The Willett plan aims to even out the glucose roller coaster through an emphasis on foods with low glycemic loads—foods that convert to glucose slowly—like whole grains, plant oils, and vegetables. This keeps blood glucose levels relatively constant, sparing the pancreas overwork. Steady blood glucose also helps keep the appetite in check, which makes maintaining a healthy weight easier, says Willett. So instead of high carb, low fat, one might summarize the Willett plan’s directive as good carb, good fat.


“People are being told to reduce fat and eat more carbohydrates. For many people, particularly overweight people with a high degree of insulin resistance, that produces exactly the opposite of what they need,” says Willett. Randomized trials, he says, show that people on low-fat diets generally lose two to four pounds after several weeks but then gain back the weight even while continuing the diet. “Most of them would be better off reducing carbs, switching to better carbs, and increasing their intake of healthy fats.”

Willett, like virtually every other nutrition researcher, advises eating vegetables in abundance, consuming alcohol in moderation, and taking a daily multivitamin to cover nutritional gaps. He also touts fish as a source of protein and heart-protective n-3 fatty acids, which are also known as omega-3 acids. (Those who worry about mercury contamination in fish got some good news recently: In one study conducted in the Seychelles, a group of islands in the Indian Ocean, scientists from the University of Rochester Medical Center tracked pregnant women who ate an average of 12 fish meals a week, about 10 times the quantity of fish eaten by the average American. “We’ve found no evidence that the low levels of mercury in seafood are harmful,” said lead author Gary Myers. Moreover, various tests indicated that the women’s children suffered no adverse cognitive, behavioral, or neurological effects.)

High on the list of food ingredients Willett counsels avoiding are hydrogenated fats, often referred to as trans fats, which are found in shortening, margarine, deep-fried foods, and packaged baked goods. That advice was controversial when Willett published a groundbreaking paper on the subject in 1991, but it has since become close to dogma. “Both controlled-feeding studies that have examined the effects of trans fat on blood cholesterol and epidemiological studies of trans-fat intake in relation to the risk of heart disease and diabetes indicate they are considerably worse than saturated fats,” he says.

Daily exercise is essential, Willett adds, and he confirms the often-cited advice that walking is the best choice for many people. The Nurses’ Health Study revealed a “very strong link” between walking and protection against heart disease: Women who walked an average of three hours a week were 35 percent less likely to have a heart attack over an eight-year period than those who walked less. It may seem odd that Willett includes exercise in his Healthy Eating Pyramid, but he is adamant that exercise and diet cannot be teased apart. “It doesn’t have to be extreme. I run along the Charles for 25 minutes most mornings.” A half hour daily of moderate activity offers “impressive health benefits,” he says, but there is “added benefit for greater intensity for longer times.”

Willett’s more iconoclastic conclusions include the heretical notion that soy—touted as a miracle food that fights cancer, obesity, and virtually every other human ill—may have “a dark side.” He points to a British study in which 48 women with suspicious breast lumps were randomly assigned to receive either no supplement or one containing soy isoflavones (a compound in soybeans molecularly similar to estrogen) for 14 days. Those taking the supplement showed substantially more cell growth in the tissue removed than the women who were not taking the soy. Another troubling study showed memory loss and other cognitive declines in elderly Japanese men in Hawaii who stuck to their traditional soy-based diet, as opposed to those who switched to a more of a Western diet. “In moderation, soy is fine,” says Willett. “Stuffed into everything, you could get into trouble.” And soy isoflavone supplements, he counsels, should be regarded as “totally untested new drugs.”

Graphic by Don Foley

Walter Willett finds it useful to present dietary information in pyramid form, with the broad base representing exercise and foods to emphasize and the small tip showing foods to avoid. “It’s simple,” he says. “It gives you a sense of priorities.” But he argues that the federally sanctioned USDA Food Guide Pyramid is deeply flawed. “The thing to keep in mind about the USDA pyramid is that it comes from the Department of Agriculture, the agency responsible for promoting American agriculture, not from agencies established to monitor and protect our health,” he says. Willett’s alternative Healthy Eating Pyramid draws a distinction between good and bad fats, between whole-grain and refined carbohydrates, and between healthy and problematic sources of protein. It also moves potatoes out of the vegetable category altogether. “Potatoes should be counted as starches. They are converted to glucose as fast or faster than pure table sugar,” he says. —B. L.