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In 2007, the Food and Drug administration approved the first ever over-the-counter diet drug. Alli, as the pill was (and still is) called, could be taken by anyone, without a prescription. And it worked, so long as those who took it also maintained a healthy lifestyle.

That last bit—persuading people who take diet drugs to also eat well and exercise—is the oft overlooked key with weight-loss remedies. And GlaxoSmithKline, which manufactures the drug, knew it. Marketing around the pill made it clear that Alli was not some miracle drug.

But getting people to treat diet drugs for what they are—helpers, not fix alls—is actually a lot harder than it sounds. Some diet drugs have been shown to work. But a growing pool of research suggests people are prone to use them improperly.

"There's a funny, kind of counterintuitive thing that happens when many people take weight-loss drugs: they gain weight," said Amit Bhattacharjee, an assistant professor at The Tuck School of Business, whose research focuses on consumer beliefs and well-being. "But it isn't necessarily because the drugs themselves don't work."

Bhattacharjee has a new study titled 'The Perils of Marketing Weight-Management Remedies,' which looks closely at how the way in which weight-loss drugs are pitched to people can significantly affect the way in which people understand them.

In the study, Bhattacharjee and co-authors Lisa Bolton of the Smeal College of Business and Americus Reed II of The Wharton School report that advertisements for diet drugs can lead people to believe, falsely, that weight-loss remedies are more powerful than they actually are. That misunderstanding, they argue, has a subtle but profound effect on how people approach nutrition and health, even before actually taking a drug.

And the consequences can be largely negative.

People, the researchers found, tend to eat worse after merely being exposed to advertisements for diet drugs. Instead of viewing weight-loss remedies as part of a system of interventions—along with healthy eating, exercise, and other measures—people seem to mistakenly believe that by taking a drug they can somehow stop watching how much ice cream they ate, or how often they went to the gym. The mere (albeit illusory) presence of a remedy, in other words, led people to eat less healthfully.

If people adjust by simply being exposed to advertisements for weight loss drugs, those adjustments are only likely to be more significant when they actually take the drugs.

"In general, the misunderstanding is that if you take this drug you can lose weight without exerting effort elsewhere to help reduce the risk of gaining weight," Bhattacharjee said. "Everyone is looking for free lunch. Everyone is looking for the promise of something easy. The problem is that these things don't really exist."

(GlaxoSmithKline did not respond to a phone call seeking comment.)

The researchers, interestingly, found that people respond differently to remedies when they are called supplements, instead of drugs. When participants saw advertisements for weight-loss remedies that were referred to as supplements, their eating habits didn't change.

"There's this notion, I think, that drugs are more targeted or precise, that they do the work for you," Battacharje said. "I don't think that's the case for supplements."

Supplements are indeed less precise. They are also regulated far less than drugs in the United States. Diet drugs, almost all of which are sold only by prescription, are legally defined as treatments for a disease (in this case, obesity), while supplements are monitored by the FDA much in the same way that food is.

Supplements, however, have proven pretty unreliable as of late. Sales of dietary supplements reached $13 billion in 2013, even though there is little science to back up many of their lofty claims. A recent investigation by New York State attorney general's office, for instance, found that GNC, Target, Wal-Mart, and Walgreens, were selling misleading supplements. And 2012 Inspector General's report concluded that a fifth of all weight loss and immune system support supplements made illegal claims about their capabilities.

As Wonkblog noted earlier this year, it can be hard to figure out which work and which don't.


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Our collective susceptibility to believing a diet drug can relieve us of the need to exercise or eat well stems from a well-known and fairly prevalent phenomenon in psychology known as motivated reasoning, whereby we essentially believe things to be true because we want them to be true.

"We want to enjoy food, we want to indulge, and we want to eat tasty things," said Bhattacharjee. "But we also have these health goals; we also want to be skinny. So when something comes along that promises to let us have it all, we want to believe it so badly that we do."

The consequences of motivated reasoning, as they relate not just to weight loss, but all sorts of other interventions, is these interventions tend to have an effect that is the opposite of its intention. There's a long line of research that explores this very interplay. The phenomenon is known well enough that it even has a name: the boomerang effect. Bolton's previous research, which has focused on the consequences of marketing remedies, has shown that the effect exists not just for weight-loss drugs, but also for smoking cessation aids.

The takeaway is, on the one hand, that any diet shortcut that sounds too good to be true probably is. On the other, it's that we're so enamored with the idea of a pill relieving us of the need to take care of ourselves, that we end up marginalizing the effect of diet drugs that actually work.

In the absence of will power—or merely the preponderance of motivated reasoning—people might want to consider trying smaller, less sweeping steps—things like making healthy foods easier to eat and unhealthy foods harder to eat—which are likely better routes to weight-loss goals.

"We need to think about little interventions," said Bhattacharjee. "Things that lead people to make better, healthier choices—not antidotes that excuse lapses."