The research on obesity that has exploded

As this 2005 article began to gain attention, a renowned professor of epidemiology and nutrition at the Harvard School of Public Health, Walter Willett, had already started his own advertising campaign. Believing that Flegal’s findings were not only false but in fact dangerous, Willett and a handful of his Harvard colleagues considered their mission to be to prevent the document – which Willett deemed “very naive” and “deeply flawed” – to be taken seriously by other scientists. , practicing physicians or the public.

For more than a decade, Flegal writes, she would find herself the target of “an aggressive campaign that included slurs, mistakes, misinformation, behind-the-scenes gossip and maneuvering, social media posts and even complaints to my employer “. His essay offers insight into the sometimes political nature of science – and how difficult it is for some scientists to consider changing their minds in the face of new data. This is especially true in a field like public health, where passions are particularly strong and where the best intentions can sometimes run counter to the search for the truth.

‘A pile of garbage’

The official definition of “overweight” is a body mass index, or BMI, greater than 25 – for a person of both sexes measuring 5 feet 8 inches, the threshold would be around 165 pounds. Obesity begins at a BMI of 30, while an adult with a BMI below 18.5 is considered underweight.

Flegal’s 2005 paper used the National Health and Nutrition Examination Survey, a nationally representative sample of office-based medical examinations, to calculate the number of excess deaths associated with each category. of BMI. She and her coauthors explained the confounding factors including age, gender, race, alcohol use, and smoking. By all accounts, a BMI between 25 and 30 seemed to be the least risky, even compared to a so-called normal weight.

This study contradicted the findings of another CDC team that had been published the year before, but it was consistent with an already growing body of research indicating that “overweight” is a fairly arbitrary category.

“It wasn’t really unusual at all, except everyone treated it like it was unusual,” she says. “I thought we were right in the mainstream. But then it turned out that people didn’t want to see it.

As Flegal recounts, she realized something was going on when reporters who called her to interview her in 2005 mentioned that they had already spoken to Willett. “He had apparently started to contact the press in a preemptive manner, to insert himself into the discussion, to position himself as an expert and to provide negative and hostile comments on our article before the reporters spoke to me.” , writes Flegal in his new diary.

Meanwhile, professors at the Harvard School of Public Health quickly organized a symposium to criticize the work and accuse Flegal’s team of mistakes they say they didn’t actually make. And when Flegal gave a talk at the University of California, Berkeley, shortly after the article was published, she noticed “an unidentified young woman” standing at the door, handing out Harvard photocopies on the dangers of overweight. Critics said his article did not take into account the relative thinness of smokers or the tendency of already ill people to lose weight as their disease progressed. These two phenomena, if poorly treated in a statistical analysis, could give the impression that thinness is less healthy. But Flegal and his co-authors investigated these potential explanations and found no data to support them.

Over the years, attacks on the newspaper and on Flegal herself have continued, not only through traditional scientific channels but also in the press, in official communications from the Harvard School of Public Health (“It is clear that the Flegal study is misleading and should be ignored ”), in a 2008 textbook by Harvard epidemiologist Frank Hu, and even via bogus edits on Wikipedia. Harvard blog posts and affiliates claimed – incorrectly – that Flegal had been “demoted” to the CDC, which had “retracted” her work (in fact, the newspaper won a prestigious internal award). Former Harvard School of Public Health students have told me they remember professors denigrating Flegal’s own weight as they dismissed his research in class discussions.

A spokeswoman for the School of Public Health declined to comment.

In 2013, Flegal followed up his 2005 article with a meta-analysis – a review of published articles – in JAMA. In this research, she and her co-authors reviewed 97 studies covering nearly 3 million people. Once again, they found that overweight people were the least at risk of premature death. And once again, the journal turned the fields of nutrition and public health upside down, drawing special censorship from Willett and his Harvard colleagues.

Willett emailed the CDC director to complain, arguing that the meta-analysis had caused damage and confusion and undermined public confidence in the science. “Kathy Flegal just doesn’t get it,” he grumbled to a reporter from The Atlantic (“My name is Katherine,” Flegal notes). In an interview with National public radio, Willett said: “This study really is a garbage heap and no one should waste their time reading it.”

Flegal’s confidence in his data, his methods and his findings has never been shaken. Yet the attacks have taken their toll. “There were all kinds of little things – it was like, wow, we’re under siege here! she says. “I completely lost control of the narrative.”

Flegal retired from the CDC in 2016 and held a part-time position as a consultant professor at Stanford. With more time to reflect on her experience, she finally decided it was important to share her story. “It’s about getting rid of my chest,” she says. “But it’s also like, wait a minute, that’s not really good!” People should know that. “

Death spiral

A colleague sent Willett a link to Flegal’s latest essay shortly after a prepress version went live in June. While Flegal’s tale is inherently only one side of the story, Willett has no problem with the details as she recalls them – and absolutely no regrets.

“Her description is largely correct, and she shouldn’t have been surprised,” Willett told Ideas. “I described his journal as rubbish and I stand by it.”

According to Willett, media interest in Flegal’s findings posed a danger to public health. With much more research linking excess weight to a variety of chronic and other serious illnesses, there was too much at stake to care about propriety.

“I could just write a letter to the editor, as you usually would in a science talk, but it would come out months later and no one would see it,” he says. “I was very aware that there could be some unhappy people, but I think it was important to do it. If we hadn’t made a visible statement here, I think the public would still be wondering if it’s really good to gain weight in the overweight range. The articles published by Flegal were woefully misleading and undermined the dietary guidelines that had been in place for decades. It was basically about giving the green light to weight gain and being overweight. . . . We are talking about millions of lives lost every year because of [obesity]. It’s a death spiral as it normalizes as we look around and everyone is overweight. “

Today’s take-out food for the public remains confusing. Health authorities around the world keep the “normal” BMI threshold at 25, and many doctors still urge people to lose weight if they exceed that number. Meanwhile, Google Scholar ranks Flegal as the top most cited obesity researcher, with 250,000 citations. Willett can cite many studies that reject his findings – including a large meta-study, published in The Lancet, to which he and his Harvard colleagues contributed in 2016 – but many others confirm them.

“She presented it very carefully – her 2013 meta-analysis was the gold standard,” says Diana Thomas, a math professor at the United States Military Academy at West Point, who studies weight statistics. body, nutrition and exercise. “She’s a person who loves numbers – she just follows the numbers. The numbers generate hypotheses. The next question is “Why? “

Why would it be healthier to be slightly above the “normal” BMI weight range? This question has yet to be fully answered, and Thomas says researchers in the field can only wonder if further progress could have been made if Flegal’s work had not been hampered by controversy. It is also disturbing, she notes, to speculate on what might have happened to Flegal’s career had she not been a senior government scientist, with secure employment and without needing to apply for a grant.

Indeed, while Flegal’s decision to write about his experience is unusual, such heated scientific arguments are less rare, and many targets, especially students and non-tenured professors, may be less able to retaliate.

“The behaviors Dr Flegal reports receiving would have surprised me early in my career, as I did not understand how flawed the tactics many academic and scientific colleagues are willing to use to combat ideas and data are vicious. malicious and unscientific. don’t like it, ”says David Allison, dean of the Indiana University School of Public Health and a biostatistician who has also done research on obesity. “Today such reports sadden me but do not surprise me.”

To Alice Dreger, a science historian whose 2015 book “Galileo’s Middle Finger” features a series of case studies on the clashes between science and activism, Flegal’s account also sounded familiar.

“Sometimes paradigms make it very difficult for people to see the data,” she says. “And I think that’s what we’re looking at here. It’s a good idea that you can have a situation where everyone is moving with the data, but people’s egos get tangled up with their theses. To abandon one’s thesis is, on a certain level, to abandon one’s identity.

For her part, Flegal was pleased with the response to her latest essay, which included thousands of posts on Twitter, some from fellow scientists thanking her for speaking out about what they say is an important topic. But she also wonders if things could have turned out differently if she hadn’t been embroiled in such a heated controversy. Has his research led to policy changes? Could it have informed better health and nutrition guidelines?

“I thought it was a very good article,” she says. “But no one paid as much attention to our article itself as I would have hoped. And it was very disappointing.

Amy Crawford is a freelance reporter in Michigan. Follow her on Twitter @amymcrawf.


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