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Walter Willett — last seen expressing sympathy for the health effects of living in international poverty after blaming the humble potato for the nation’s love handles — apparently finds any evidence that moderate overweight status isn’t an immediate death sentence problematic. He fears that that evidence might even make people side with personal responsibility and consumer choice instead of the “administrative Leviathanthat his political allies established to forbid the purchase of large-ish soft drinks.

That creates an ethical dilemma when, as has repeatedly occurred, other researchers present evidence that the optimal body mass index for life expectancy isn’t “as low as possible” and may in fact qualify as “overweight” in the government’s tables. So, Willett dismissed those findings for political purposes, calling them a “pile of rubbish.”

But that earned a rebuke from the editorial board of Nature, the prestigious scientific journal. They write:

It is more difficult, from a scientific perspective, to agree that these findings should not be published and discussed openly, warts and all, purely because they blend uncertainty into a simple mantra. Make things as simple as possible, Einstein said, but no simpler. And simple, black-and-white messages can cause confusion of their own. All things in moderation — and that should include the language we use.

The activists worry that if information that conflicts with the bumper-sticker version of their message—“Fat is bad! Eat nothing but kale!”—gets out, people might get the wrong idea even if it doesn’t conflict with the main thrust of that advice. The studies showing that an “overweight paradox” exists still find that the truly obese tend to live shorter lives, but they do sap the “We must ban all the potatoes or else we will all die” hyperbole out of the room. The same thing should happen with the Institute of Medicine’s recent report on salt consumption, which should put Michael Jacobson’s wild-eyed rhetoric about “deadly white powder you already snort” to bed.

That isn’t to say that there isn’t some valid concern. People who are obese (or who eat too much salt) shouldn’t take these “shades of grey” (to borrow Nature’s phrasing) as license to do whatever they want with no consequences. People still need to exercise responsibility. That includes “public health” researchers too.