The researchers suggest it's odd health plans would shun obesity coverage while employers, often in conjunction with insurers, are aggressively pushing wellness programs aimed at curtailing obesity. It would seem intuitive for insurers to seek to prevent obesity and the myriad of expensive conditions it leads to.

"The irony is that untreated obesity leads to a host of chronic diseases — diabetes and heart disease — that wind up costing health plans more," says Fatima Cody Stanford, a Harvard physician who focuses on obesity treatment. "The current situation makes little sense, financially or medically."

The Affordable Care Act included provisions that required insurance plan to cover certain obesity-related treatment. Insurers must cover screening and counseling for obesity at no cost to the patient.

However, more aggressive interventions, such as surgery, are not required by law. And because surgery is so expensive, it is likely that some health plans do not see whatever risks the procedure reduces as necessarily saving the insurer money in the long-term. In addition, complications from the surgery are common, leading to additional costs to the insurer.

Joe Nadglowski, president of the Obesity Action Coalition, says in a statement that the status quo is unacceptable.

"Our members report heartbreaking struggles to obtain insurance coverage for services like bariatric surgeries and obesity medicines that are necessary to reduce and prevent obesity from ravaging their health," he says. "Sometimes they are outright denied coverage and presented with absurd hurdles that have the same effect."