Eat, drink — and be happy?

Ah, Memorial Day. It’s a holiday that encourages every red-blooded American to do two important things. The first, of course, is to remember those brave men and women who have fallen in the line of duty. The second is to eat junk food and barbecue and drink a lot of alcohol, soda and lemonade.

The second Memorial Day rule is no small thing, particularly in an era a lot of people say is marked by an epidemic of obesity. As Americans get rounder, public health specialists devise new ways to shame and punish us for — I mean discourage us from — eating, drinking and otherwise inhaling things that are harmful to our bodies. Tradition dictates, however, that on Memorial Day, we all get a pass.

Over the last several years, skinny activists have begun to blame fat people for the rising costs of healthcare. A November study out of Emory University projects that by 2018, the U.S. could spend up to $344 billion on healthcare costs attributable to obesity. In response, about 40 states have already adopted “sin taxes” on their latest target, sugary sodas and juice drinks. The remaining states, including California, are debating whether to follow suit.

Unfortunately, like every other issue in this country these days, the sin-tax debate generally divides into two simplistic camps, in this case the “we know what’s best for you” liberals and the “I can do whatever the heck I want” libertarians. And, as with most issues that are held hostage by ideologues, what gets lost are the actual needs and motivations both sides presume to represent.

But now comes a new study out of the University of Michigan’s Institute for Social Research that reminds us why people drink soda and eat potato chips and generally engage in behaviors that they may know are bad for them. And it’s not because they’re stupid or lazy or have a “let us eat cake” libertarian death wish. According to the institute’s director, James S. Jackson, “People engage in bad habits for functional reasons, not because of weak character or ignorance.”

Comfort food, it turns out, is genuinely comforting. According to Jackson’s study, in fact, a lot of bad things we do to cope with stress actually help. Although these strategies are physically detrimental in the long term, they can be, in Jackson’ words, “effective in ‘preserving’ … mental health” in the short term.

This is common sense, right? Anecdotally we know we eat food that is high in fats and carbohydrates when we’re anxious. And there is data that show alcohol consumption reduces feelings of stress. Similarly, smoking and nicotine ingestion are often reported to result in mild euphoria, increased energy and a sense of well-being.

Of course, the researchers are not condoning or dismissing the public health problems these behaviors induce. What they’re doing is putting them into context. And they, or their findings, suggest that the public health debate about bad behaviors needs a more complete understanding of the word “health.” In other words, you have to start by admitting that bad behaviors really aren’t all bad. They “may have adaptive, neurological effects that alleviate negative psychological and physiological states.”

For many people, the researchers argue, especially the poor, “the short-term benefits of reducing anxiety, depression and frustration may psychologically outweigh the risk of poor long-term physical health from behaviors” such as overeating, drinking or smoking. It’s more than possible that obese people will die younger but happier than thin ones.

So where does that leave us when it comes to public policy? Well, shaming, blaming, punishing and even championing free will are all beside the point. If we can’t improve the conditions that create our chronic stress, we’ll go for the milk shake, the chips and the bacon cheeseburger every time — and to heck with the cost, the humiliation and even the consequences.

The sin-tax debate hinges on the notion that choosing the cheeseburger is idiocy. Either you have to be “incentivized” out of it for the sake of the collective good, or allowed to wallow in it for the sake of freedom. But the Michigan research undermines both arguments — because eating a cheeseburger isn’t all that idiotic. But our way of trying to fix obesity is.

Happy Memorial Day. Pass the Diet Coke.

grodriguez@latimescolumnists.com