The Science is Settled...

...As long as you agree with me. Nature rebukes Harvard nutritionist for 'unscientific' behavior

In an extraordinary editorial and feature article, Natureone of the world’s pre-eminent scientific journals, has effectively admonished the chair of the Harvard School of Public Health’s nutrition department, Walter Willett, for promoting over-simplification of scientific results in the name of public health and engaging in unseemly behavior towards those who venture conclusions that differ to his.

Willett, who is one of the most frequently quoted academic sources on nutrition in the news media, appears to have crossed a Rubicon when he denounced Katherine Flegal, an epidemiologist at the US National Center for Health Statistics, for publishing a study that showed people who were overweight (but not obese) lived longer than those deemed normal weight. “This study is really a pile of rubbish, and no one should waste their time reading it,” he told National Public Radio.

Calling someone else's study "a pile of rubbish" is kind of harsh, but within the bounds of scientific discourse.  Try publishing a study that contradicts Anthropogenic Global Warming, for example.  However in making such an accusation, it helps to have the facts on your side.

Willett is well know for being forthright in his views; but describing Flegal’s work as a “pile of rubbish” appears to have ticked off obesity researchers and biostatisticians alike, for this isn’t the first study to arrive at such a finding – and researchers lined up to tell Nature why it was plausible: a little extra weight for those who were older or older and ill, could help rather than hurt. Moreover, Flegal herself responded with some sharp statistical criticism of Willett’s “rubbish” thesis.

And it turns out that Willett has generated some controversy in some of his own work.

There was also a spectacular irony in Willett’s complaints about Flegal’s study that will not have gone unnoticed in scientific circles, namely that Willett was the co-author of a study published last fall that generated enormous controversy when its dramatic conclusions were retracted at the last minute by the publicity team at Harvard’s teaching hospital, Brigham and Women’s. The study had been promoted to the media as showing a link between aspartame and cancer: “The truth isn’t sweet when it comes to artificial sweeteners,” said the press release. But the truth was that the statistical findings were so weak and confusing that no such claim could be supported, especially given that many systematic reviews of the evidence on aspartame had not found any such link.

As they say, there are lies, damn lies and statistics. What really seems to have pissed Willett off was the assertion that a little overweight could be better than what the guidelines were suggesting, even if for a slightly odd reason:

It also emerged that the study had been rejected by six journals, before being published in the American Journal of Clinical Nutrition, where Willett is a member of the editorial board. “I do think this finding is strong enough to justify further study on aspartame and cancer risk,” Willett told NPR.

Rejected by six journals? I'll say this, the guy is persistent if nothing else.

In other words, findings, no matter how vague, are still good when Willett is involved in the study, even though they muddy the public health message on aspartame, which is that it is safe; but findings, even if they are stronger – as with Flegal’s – are bad when they muddy the public health message on weight gain.

Scientists, as much as anyone else, fall in love with their own ideas, and protect them like a mother  protects a child.  It isn't 'scientific', but it's human.  Science will eventually arrive at the truth, but sometimes there are bumps, pot holes and road blocks along the way.