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We now know that obesity, a chronic disease that affects almost half of the United States population and contributes to millions of deaths worldwide, isn’t just about how much you weigh. A huge variety of factors, from physical and mental health to genetics and upbringing, all contribute to the national obesity epidemic—and so do the human body’s own defense systems, which try to hold onto weight whenever possible. Like any other complex and multifactorial disease, clinicians say that obesity treatment requires a complex approach. But the system of billing classifications that healthcare professionals use is lagging behind this understanding, leading to suboptimal care: that’s the message of a new paper in the journal Obesity.

These diagnostic codes are surprisingly important. Because they allow physicians to describe what they’re doing and why so they can get paid by insurers, the codes can influence the way doctors think about disease and what interventions they offer. Currently, medical professionals treating obesity are only able to bill using a simple diagnostic code provided by the International Classification for Diseases (ICD): E66.0, defined as “obesity due to excess calories.” To arrive at that diagnosis, a healthcare practitioner relies only on someone’s Body Mass Index (BMI) as a metric. But BMI isn’t necessarily a good indicator of how much adipose tissue (otherwise known as fat) someone has, meaning that the diagnosis may be inaccurate.

Beyond that, though, saying that people are obese because of “excess calories” contributes to a damaging perception that obesity is a lifestyle choice, says W. Timothy Garvey, one of the new study’s authors. It doesn’t encourage medical professionals to think about obesity as the chronic illness we now know it is—the result of complex factors that can differ greatly between patients.

Garvey and coauthor Jeffrey Mechanick, a Mount Sinai University endocrinologist, are proposing a new classification system that they hope will be adopted by the ICD to replace “obesity due to excess calories.” Instead doctors would bill for ABCD, or “adiposity-based chronic disease,” which would connect to four different kinds of codes related to treatment.

Adopting the system would give healthcare providers more leeway to provide individualized and evidence-based care for obesity, they write, rather than simply telling patients that they need to lose weight.

That’s why he and his coauthor propose dividing the diagnosis of ABCD into four possible ICD codes, denoting the related health treatment that’s taking place. “A” codes would be related to weight gain and other obesity-related issues that are rooted in an existing disorder or health issue; B codes would be related to BMI; C codes would be related to heart or body complications that could be treated with weight loss; and D codes would indicate how serious the complications are. Secondary codes could help tailor the treatment further. The result is a lot more complicated than a diagnosis of “obesity,” but it would go a long way toward getting health professionals—and insurers—to treat the issue as a complicated disease.

Garvey believes that changing the code to reflect obesity’s complexity would prompt healthcare professionals to do more than just tell patients to lose weight. “You treat a disease to improve quality of life,” he says. “And with a chronic disease, that means preventing or treating the complications of the disease state. That’s what really improves quality of life.” When clinicians are able to bill for time spent figuring out underlying issues that contribute to obesity, he says—depression, lack of access to healthy food, injuries that prevent them from getting active—they will be more likely to spend time addressing them.

“The current coding we have in place for obesity does not take into consideration the complexity of the disease as we think about it today,” Robert Kushner, an obesity medicine physician specialist at Northwestern University, told Popular Science in an email statement. “This new coding system is a step in the right direction.”

ABCD isn’t a new diagnosis: it’s been embraced by the American Association of Clinical Endocrinologists, among other medical groups. But it could potentially be a game-changer if it’s adopted by the ICD, says Garvey. A code that recognized obesity as a chronic disease related to—but not reduced to—excess body fat would allow healthcare professionals to bill for treating all different parts of the obesity equation, and hopefully lead to better results for patients.

“At this time, coding visits with the diagnosis ‘obesity’ or anything that has the word obesity in it leads to inconsistent [insurer] reimbursement or none at all,” Rekha Kumar, the medical director of the American Board of Obesity Medicine, told Popular Science. ABCD “might encompass more aspects of the disease than just ‘obesity,’” he writes, “but the key will be whether this terminology actually changes practice and reimbursement.”

Arya Sharma, the scientific director of Obesity Canada, cautions that the proposed new codes would take a long time to go into effect. The ICD is about to release the 11th edition of its codes, which has a revised definition of obesity that still doesn’t look at it as a multifactorial disease. For ABCD to get into ICD 12, Sharma says, would be “a very slow and a very involved process.”

Although it remains to be seen whether the ICD will take Garvey and Mechanick up on their proposed reclassification, change is definitely needed. “There’s no doubt that the current ICD codes are not helpful,” Sharma says.