In this file photo dated Tuesday, June 26, 2012, two overweight women hold a conversation in New York, USA. (AP)

The body mass index (BMI) metric has triggered "historical harm," which includes racist exclusion, the American Medical Association (AMA) Council on Science and Public Health reported.

The BMI metric was long used by doctors to measure obesity, but studies show that it is an imperfect measurement that does not directly assess body fat, the medical association added.

It is measured by dividing a person's weight in kilograms or pounds by the square of height in meters or feet.

According to the report, cutoffs for BMI, which range from underweight to obese, were created based on data collected from non-Hispanic white populations and do not take into account gender or ethnicity, as BMI body fat "does not account for differences across race/ethnic groups, sexes, genders, and age-span."

Moreso, women tend to have more body fat than men, and older people have more body fat than younger adults, per the CDC.

What are they saying?

“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," Dr. Jack Resneck, Jr., the AMA's immediate past president, said in a statement.

"Relative body shape and composition heterogeneity across race and ethnic groups, sexes, genders, and age-span is essential to consider when applying BMI as a measure of adiposity," the AMA said.

That means that the BMI metric does not account for the full range of eating disorders and is problematic when used to treat them, according to the report.

The metric can contribute to stigma around weight and be a barrier to accessing care for people with eating disorders, said Lauren Smolar, a spokesperson for the National Eating Disorders Association. "Eating disorders occur to people at higher weights but are diagnosed at a much lower rate because health providers do not look into additional health concerns beyond body size," Smolar said.

What happens next?

Moreover, physicians should be aware of issues with BMI and alternative measures to diagnose obesity, the report said.

The new policy suggests that BMI could be used in conjunction with a host of other measures in clinical settings, such as visceral fat; body adiposity index; body composition; relative fat mass; waist circumference; and genetic or metabolic factors.