Read more of Daniel Engber's columns on obesity and health care reform.
Not long after the attack on Pearl Harbor, in the winter of 1942, physiologist A.J. Carlson made a radical suggestion: If the nation's largest citizens were charged a fee—say, $20 for each pound of overweight—we might feed the war effort overseas while working to subdue an "injurious luxury" at home.
Sixty-seven years later, the "fat tax" is back on the table. We're fighting another war—our second-most-expensive ever—and Congress seems on the verge of spending $1 trillion on health care. Once again, a bloated budget may fall on the backs of the bloated public. Some commentators, following Carlson, have lately called for a tax on fat people themselves (cf. the Huffington Post and the New York Times); others, like a team of academics writing in the current issue of the New England Journal of Medicine, propose a hefty surcharge on soft drinks instead.
The notion hasn't generated much enthusiasm in Congress, but fat taxes are spreading through state legislatures: Four-fifths of the union now takes a cut on the sales of junk food or soda. Pleas for a federal fat tax are getting louder, too. The New York Times recently endorsed a penny-per-ounce soda tax, and Michael Pollan has made a convincing argument for why the insurance industry may soon throw its weight behind the proposal. Even President Obama said he likes the idea in a recent interview with Men's Health. (For the record, Stephen Colbert is against the measure: "I do not obey big government; I obey my thirst.")
For all this, the public still has strong reservations about the fat tax. The state-level penalties now in place have turned out to be way too small to make anyone lose weight, and efforts to pass more heavy-handed laws have so far fallen short. But proponents say it's only a matter of time before taxing junk food feels as natural as taxing cigarettes. The latter has been a tremendous success, they argue, in bringing down rates of smoking and death from lung cancer. In theory, a steep tax on sweetened beverages could do the same for overeating and diabetes.
It may take more than an analogy with tobacco to convince voters. As my colleague William Saletan points out, the first step in policing eating habits is to redefine food as something else. If you want to tax the hell out of soda, you need to make people think that it's a drug, not a beverage—that downing a Coke is just like puffing on a cigarette. But is soda as bad as tobacco? Let's ask the neuropundits.
Junk food literally "alters the biological circuitry of our brains," writes David Kessler in this summer's best-seller, The End of Overeating. In a previous book, Kessler detailed his role in prosecuting the war on smoking as the head of the FDA; now he's explaining what makes us fat with all the magisterial jargon of cognitive neuroscience. Eating a chocolate-covered pretzel, he says, activates the brain's pleasure system—the dopamine reward circuit, to be exact—and changes the "functional connectivity among important brain regions." Thus, certain foods—the ones concocted by industrial scientists and laden with salt, sugar, and fat—can circumvent our natural inclinations and trigger "action schemata" for mindless eating. Got that? Junk food is engineered to enslave us. Kessler even has a catchphrase to describe these nefarious snacks: They're hyperpalatable.
Try as we might, we're nearly powerless to resist these treats. That's because evolution has us programmed to experience two forms of hunger. The first kicks in when we're low on energy. As an adaptation, its purpose is simple enough—we eat to stay alive. The second, called hedonic hunger, applies even when we're full—it's the urge to eat for pleasure. When food is scarce, hedonic hunger comes in handy, so we can stock up on calories for the hard times ahead. But in a world of cheap food, the same impulse makes us fat.