The truth on foods and fats
Early studies in animals indicated trans fats might lead to heart disease. They increased LDL, the "bad" cholesterol, while depressing "good" HDL cholesterol. In 1993, the Nurses' Health Study found a 50 percent increase in heart disease associated with trans fats in food. A year later, Willett dropped another bomb: People who ate the most trans-fat-rich food were two times as likely to have a heart attack as were people who ate less of these fats.
Joint effort. By the spring of 1994, Willett and CSPI had joined forces to persuade the U.S. Food and Drug Administration to require trans-fat labeling on food products. Willett's 1997 study estimated that use of hydrogenated oils was resulting in 30,000 heart-disease deaths per year, representing "the biggest food processing disaster in U.S. history."
These efforts did not endear Willett to the food industry. Indeed, some companies refused to support conferences if Willett was invited to speak. But by 2002, the evidence was overwhelming: The Institute of Medicine reported that the safe amount of trans fat in the diet is zero. In July 2003, the FDA ruled that trans-fat food labeling must begin by January 2006. But Willett no longer believes labeling is enough. In May, he and 27 other scientists urged the FDA to remove hydrogenated oils from the "generally recognized as safe" list of food additives.
Most recently, Willett has been championing "the glycemic index" as a way of judging which foods may be fueling the epidemics of obesity and diabetes. The GI was developed as a lab tool to rank how quickly carbohydrates raise blood sugar. Willett found an association between eating some foods with a high glyce-mic index--such as potatoes and white rice--and diabetes and heart disease. In theory, foods with a high GI release sugar in-to the blood rapidly but leave people hungry, leading to overeating and weight gain.
The problem with this theory, says Xavier Pi Sunyer, director of the New York Obesity Research Center, is that carbohydrates have not been associated with a high frequency of diabetes. "Asians traditionally ate a high-carbohydrate diet with a high glycemic index--lots of rice, low in protein and fat, and they had low rates of diabetes, heart disease, and obesity," he says. Others agree that the evidence is mixed at best. Says nutritionist James Kenney of the Pritikin Longevity Center: "The No. 1 reason for diabetes is overweight. People who have lost weight and kept it off do not eat a low glycemic index diet--they eat a low-fat diet and exercise a lot."
Whether the GI concept will play a major part in reversing obesity is unclear. But in the end, no one denies that Willett's role in nutritional science is enormous. "I think what we've contributed is the magnitude of the importance of diet and lifestyle to health," he says. One small regret: "I never connected with the olive-oil presser." When Willett arrived, the man was on holiday.