You might remember Barry Popkin as one of the scientists who helped fuel a string of myths about high fructose corn syrup (HFCS). Popkin coauthored a study with George Bray in 2004 in which the duo blamed HFCS as a potential cause for the rise in obesity rates. Even top food cop Michael Jacobson derided the study, stating that "the authors of this paper misunderstand chemistry, draw erroneous conclusions and have done a disservice to the public in generating this controversy." Now Popkin admits his error. But like the mythical boy who cried “wolf,” he’s asking us to trust his judgment about his latest nutty crusade: an endorsement of heavy taxes on soda.
Popkin first came to his senses about sweeteners last year, producing a scientific report rejecting his own 2004 theory and finding “no special link” between HFCS and obesity. And in an interview published today, Popkin further backs off his previous egg-on-face speculation that HFCS is responsible for obesity:

We were wrong in our speculations on high fructose corn syrup about their link to weight… People are always looking for enemies. We said it needs to be studied more, that there need to be further studies. Anybody who talks about foods gets demonized or glamorized … You can’t stop doing what you think is right when science backs you up.

But with the ink on his sweetener mea culpa still drying, Popkin is quick to keep his soda non grata momentum going:

The taxes have been rejected but we’re not ready yet. It will take a state or two to do it, but I think it will come in other countries first. There are a lot of people who say we should leave everything unfettered, but we’re getting close.

Just like last time around, Popkin’s position on soda taxes isn’t backed up by much actual science. A 2008 paper calculated that a 1-percentage-point increase in a soda tax would reduce the average body mass index by just 0.003 units (i.e., a minuscule amount). This year a scientific review concluded that there would have to be a $9 tax on a 75-cent can in order to have a significant effect on consumers’ weight. And there’s a wealth of research showing that soda isn’t responsible for childhood obesity.
Barry Popkin might want to carefully consider his own words that “people are always looking for enemies”—in his case, sugary drinks. The way we read his take on soda taxes, he’s basically saying “Oops … I totally blew it on HFCS. But you’ve got to trust me this time.”
Right.