Normally I'd write a clever intro for a post like this, but I honestly can't think of anything else to say in this case: there's a professional journalist who thinks we should tax diet soda, or else consider ourselves racists. His name is Gene Balk, the "FYI Guy" at The Seattle Times.
FYI Guy's argument goes like this: taxing soda is a good way to reduce obesity. However, taxing only sugary soda is discriminatory in practice because minorities consume more sugary sodas than white and Asian people; therefore, we should also levy an equitable tax on diet sodas, since white and Asian people consume more diet sodas.
This argument is so puerile, so fallacious in so many ways, that I'm a little offended by my willingness to debunk it. But I'm going to do it anyway. For science. So here we go: there isn't one bit of good science to justify FYI Guy's proposal. And were such a simpleminded plan implemented, it would backfire.
The logic behind a soda tax is pretty simple. Though they don't do much to reduce obesity in practice, proponents push for soda taxes because soda is fattening. Whether because sugar represents empty calories in our diets or because it's uniquely fattening, most experts will agree that we should consume less of it. And indeed research shows that as our sugar consumption increased, so did our propensity to gain weight. Hence a tax on sugar-sweetened foods and drinks to reduce their consumption.
Now, the only possible reason to levy a tax on a diet soda is because it affects our health in the same way a regular soda would. Unfortunately for Balk, there isn't a shred of evidence to justify this conclusion. I've discussed most of the relevant research here, and there is no way to defend the claim that diet soda is at all harmful to human health. Disagree all you want, shout "N=1" until you're blue in the face. I don't care. But show me some good science if you're going to make sweeping claims about the dangers of diet soda, especially if you're trying influence public health policy.
To his credit, FYI Guy did try to muster some science to defend his position. But what did he bring to the table? A review paper claiming that diet soda can stall weight loss, which we took apart in January. The article was based on weak observational data, animal studies and questionable assertions not born out by the available science. But even if Balk and his dubious source were correct, stalling weight loss and causing weight gain are not the same thing. Are we really going to tax people because they consume a drink that doesn't make them fat? You're effectively taxing people for making healthier choices at that point. This is the dumbest possible approach to tackling the obesity epidemic.
FYI Guy also claimed that diet soda may contribute to type 2 diabetes and obesity based on two observational studies which show that obese, diabetic people tend to drink more diet soda than their skinnier, insulin sensitive counterparts. But again, as we've discussed before, it's more likely that obese people drink more diet soda because they're trying to cut out some extra calories in order to lose weight and bring their blood sugar under control. Balk is just being sloppy here.
The rest of FYI Guy's argument is just a summary of demographic data showing that minorities drink more regular soda, because they're poorer and less educated than white and Asian people. That's true, of course. But why it's any of FYI Guy's business, or anyone else's for that matter, is beyond me. Some people are smarter than others, yes. However, we're all adults. And if we can be trusted to vote, drive cars and go to work every day, I think we can decide what kind of soda we'd like to drink.