AMA votes to move away from BMI

At its annual meeting, AMA voted to adopt a new policy that moves away from using BMI alone when assessing whether a patient is at a healthy weight.

In a report, an AMA subcommittee wrote that BMI does not differentiate between fat and lean mass or account for where body fat is located. According to studies, fat that accumulates around the stomach may be more harmful than fat that accumulates in the thighs or legs.

In addition, BMI is primarily based on data from non-Hispanic white populations, which makes it difficult to apply to a broader population. For example, studies have shown that Asian, Hispanic, and Black patients have a higher risk of developing type 2 diabetes at lower BMIs compared to white patients.

In the new policy, the organization noted that the metric had been used for "racist exclusion" and had caused "historical harm" to patients.

Going forward, AMA recommends physicians use BMI in combination with several other factors when assessing patients' health and weight, such as visceral fat levels; body adiposity index; fat, bone, and muscle percentages; and genetic and metabolic factors. The organization also noted that BMI should not be used as a sole criterion for denying insurance reimbursement.

"There are numerous concerns with the way BMI has been used to measure body fat and diagnose obesity, yet some physicians find it to be a helpful measure in certain scenarios," said Jack Resneck, Jr., AMA's immediate past president. "It is important for physicians to understand the benefits and limitations of using BMI in clinical settings to determine the best care for their patients."

"It's a pretty big shift," said Cynthia Romero, director of the M. Foscue Brock Institute for Community and Global Health at Eastern Virginia Medical School who helped develop the new policy. "Now we have to be truly more mindful and more holistic when it comes to patient care."

Why replacing BMI will likely be difficult

According to Francisco Lopez-Jimenez, a cardiologist at Mayo Clinic, AMA's new policy may speed up the slowly changing paradigm around BMI and weight. "This was an unequivocal statement," he said. "They were not shy."

However, Lopez-Jimenez noted that "paradigm changes take more than a single statement" and will require "different people, different societies, you have to hear this over and over" before being widely accepted.

Angela Fitch, president of the Obesity Medicine Association, said one of the biggest difficulties of changing the status quo when it comes to BMI is that "the most robust science is around BMI as a measure." Most trials and research on obesity treatments have all focused around BMI cutoffs because the data is easy to collect.

"We're already moving away from [BMI] philosophically, and that's good," Fitch said. But "we need the science to catch up with the movement." She also noted that studies testing other weight metrics are often lengthy and difficult to conduct.

Currently, many areas of medicine, including fertility treatments and surgery eligibility, rely on BMI to screen and assess patients for potential risks. However, some physicians argue that that BMI cutoffs are sometimes too restrictive and prevent patients from getting care they need.

"It can be very challenging when somebody cries out for help and is seeking help, but they don't receive the help that they feel they need," said Reilly Bealer, an incoming medical resident who worked with other students to advocate that AMA amend its BMI policy. Notably, Bealer herself was initially unable to receive treatment for an eating disorder since her BMI was not below 18.

In general, "I think the trend is moving away from BMI, but these entrenched issues don't fade away easily," said Loren Schechter, a plastic surgeon at Rush University. "Unfortunately, oftentimes you need a lot of literature and experience to do away with some of these things that have been ingrained in the system for a while." (Blum, New York Times, 6/15; AMA press release, 6/14; Trang/Chen, STAT, 6/13; Chen, STAT, 6/16)

Writing for the Harvard Business Review, Ryan Howard and Michael Englesbe of the University of Michigan explain how programs in Michigan, North Carolina, and England leverage specialty care visits to screen for chronic illness and other foundational health issues — programs that can serve as models for health systems around the country.