Do Sugary Sodas Make You Fat?

| Thu Oct. 28, 2010 6:11 PM PDT

Over at the Volokh Conspiracy, Jonathan Adler writes:

Politicizing Soda Science

Today’s NYT reports on how New York City’s health commissioner pressured his staff to create a scary anti-obesity ad campaign, featuring this ad, even if it meant stretching the available scientific evidence on the potential health consequences of drinking a can of soda per day. In the end, they produced an ad that was “defensible” because, as one participant in the discussions put it, the ad’s language was “broad enough to get away with.”

Now, there are a bunch of things you might say about this right from the start. Maybe governments shouldn't be in the business of running nanny state ads about personal nutrition. Maybe this particular ad was disgusting and shouldn't have been released. Maybe obesity isn't really that big a deal in the first place. But those weren't the issues at stake. Rather, it was this single sentence in the ad:

Drinking 1 can of soda a day can make you 10 pounds fatter a year.

What, I thought, could be wrong with that? A can of sugared soda contains about 150 calories, and adding 150 calories a day to your diet would almost certainly produce a ten-pound weight gain over the course of a year or so. There are some caveats, of course:

  • If you cut out 150 calories elsewhere, you won't gain any weight.
  • If you exercise more, you won't gain any weight.
  • Your exact weight gain will depend on your age, current weight, etc.
  • If you have a miracle metabolism, you might not gain any weight at all.

This all seems pretty obvious, and while you'd probably mention it in a longer piece, it hardly seems necessary in a 30-second spot. But it turns out the scientists, especially Michael Rosenbaum of Columbia, seemed to think it should all be included. The ad, he said, was "misleading in that there is no reference to energy output changes."

So I'm curious: what do you all think of this? I'm open to argument here, but it seems crazy to me, less a politicization of science from the health commissioner than a case of geekdom run amok among the scientists. I mean, if you can't tell people that adding a bunch of calories to your diet will make you gain weight, what can you tell them?

POSTSCRIPT: And while I'm at this, can I complain once again about how journalistic conventions can ruin a story? It's actually hard to tell exactly what happened here because the reporter insisted on "adding value" by not relating things in a simple chronological fashion. Nor does she tell us what the original sentence they were arguing about was. It's a real mess.

UPDATE: Via comments, I do see one problem with this ad that I didn't notice before. The phrase "10 pounds fatter a year" might lead you to believe that you're going to gain ten pounds years after year. In fact, you'd gain (about) ten pounds and then just stay there.

This interpretation didn't occur to me when I saw the ad. However, it's a plausible one. Something like "10 pounds fatter in a year" might be better.

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