Walter Willett

In 2021, Flegal published an article in the journal Progress in Cardiovascular Diseases accusing Willett and some of his Harvard School of Public Health colleagues of being part of "an aggressive campaign that included insults, errors, misinformation, social media posts, behind-the-scenes gossip and maneuvers, and complaints to her employer." Flegal wrote that the goal Willett and his allies "appeared to be to undermine and discredit her work," and that, "The controversy was something deliberately manufactured, and the attacks primarily consisted of repeated assertions of preconceived opinions." Flegal also questioned Willett's competence to criticize her team's statistical research, as he "was not a statistician and had no expertise in estimating the number of deaths associated with obesity."

In 2016, Semantic Scholar AI program included Willett on its list of top ten most influential biomedical researchers.

Willett's epidemiological research has been criticized by nutritionists and other researchers promoting an "obesity paradox" (Hughes, 2013). They believe he lacks a rigorous scientific base and often has contradictory findings.

Willett has been a high-profile critic of research into the health risks of obesity by American epidemiologist Katherine Flegal and her colleagues at the Center for Disease Control and Prevention's National Center for Health Statistics, going so far as to call it a "pile of rubbish ... No one should waste their time reading it." In 2013, the journal Nature ran an editorial rebuking Willett for the style and manner of his criticism, saying it misrepresented the complexity of the science involved and used inappropriate language in doing so.

Willett is perhaps best known for his 2001 book Eat, Drink, and Be Healthy and the ensuing controversy over it. The book presents nutritional information and recommendations based on what was then the consensus of nutrition scientists, and is critical of many misconceptions about diet and nutrition, including ideas presented by guidelines from American organizations such as the USDA. Willett is frequently quoted by the media in articles regarding nutrition.

Walter C. Willett (born June 20, 1945) is an American physician and nutrition researcher. Currently, Willett is the Fredrick John Stare Professor of Epidemiology and Nutrition at the Harvard School of Public Health and was the chair of its department of nutrition from 1991 to 2017. He is also a professor of medicine at Harvard Medical School.