As the American obesity epidemic expands, companies are rushing to fill the demand for weight loss with newer and easier-to-use products. But not all methods of weight loss are being seen as legitimate. Some experts are skeptical that insurance companies, looking to make quick gains, won’t cover anti-obesity medication.

"For things that are preventive in the long term, it makes plan sponsors think about their strategy," said Dr. Steve Miller, the chief medical officer at Express Scripts, to NPR. But weight loss comes with a longer timeline than most companies would like to accommodate. Coupled with this is a mistrust of the science, as four diet pills have earned FDA approval since 2012, yet none has managed to achieve more than mild success.

History doesn’t bode well for weight loss pills either. In 1997, the FDA famously withdrew two diet drugs, fenfluramine and dexfenfluramine, better known as fen-phen, over late-to-the-game evidence that the drugs caused problems to people’s heart valves. Even 18 years later, Miller says, insurance companies may be feeling residual fear that liabilities could crop up again.

In the U.S., obesity eats up nearly $150 billion in medical costs, which, per person, are $1,429 higher among those who battle obesity-related conditions, such as diabetes, hypertension, and heart disease, compared to people of a normal weight. But the critical point for Miller is how people go about dropping that unwanted poundage. When people’s body mass index bleeds into the 30s, where the risks of obesity really start to matter, diet and exercise alone tend to come as too little, too late. People want more, and generally that means one of two things: surgery or pills.

Some experts believe the evidence is there to support coverage. For example, they point to the American Medical Association’s 2013 decision to classify obesity as its own disease, rather than as a risk factor for disease. Dr. Caroline Apovian, director of the Nutrition and Weight Management Research Center at Boston University, argues the disease label should assign legitimacy to obesity, and thus, to diet pills.

"Coverage has to happen in order for the obesity problem to be taken care of," Apovian said to NPR. "Insurance companies need to realize it's not a matter of willpower, it's a disease."

The science, however, may be on the insurers’ side. A 2014 study found people were more likely to see themselves as healthier and choose to eat more unhealthy food if their overweight status was classified as a disease. For the researchers carrying out the study, the findings implied a sense of demotivation in the overweight subjects. In other words, the label let them see their weight as fixed, and the problem was out of their control.

Miller is inclined to agree. Insurance companies tend to shy away from weight loss programs that come with long-term upsides mixed with high risks for loose adherence. They prefer quick fixes like gym memberships, which are relatively low-cost add-ons that come with weekly minimums to qualify and can be cut short due to inactivity. Measuring the effectiveness of a pill that may take over a decade to work — if you even stick around at the job that long — is far less appealing.