In June of 2023, the American Medical Association (AMA) adopted a new policy that changed the role of body mass index, or BMI, in determining obesity. The policy calls out the “significant limitations” of the BMI and points out its history of “racist exclusion.” The AMA now recommends doctors no longer use the BMI as a standalone measure and instead incorporate other factors to determine health and obesity risk.
“A few years ago, I shifted my practice to using the BMI as one piece of information about a person’s health, and not the most important marker of health,” says Dr. Barrett. “I take it in context of other metabolic markers -- that I consider more important -- as well as lifestyle habits. For example, I look at blood pressure, blood sugar, cholesterol levels and liver enzymes.”
The BMI’s troubled history
For decades, the BMI has been the key number used to determine if you are a healthy weight. You calculate your BMI by dividing your weight by the square of your height.
In recent years, BMI has been under fire. A mathematician developed the initial concept in Belgium in the 1830’s. Another 140 years later, in the 1970’s, a physiologist suggested the number could be used to estimate body fat. Since then, the BMI’s popularity soared as a screening tool for obesity. With 40% of American adults qualifying as obese based on their BMI, the AMA change in recommendations represent a significant shift in health care and clinical practice.
Some places may use your BMI beyond for reasons beyond measuring obesity. For example, BMI has been used to determine:
- Eligibility for some surgical procedures
- Life insurance policies
- Employer-based wellness programs
- Fertility treatment options
However, the BMI is not a perfect measurement. Some criticisms include:
- While body fat percentage often is a reliable indicator of health risks, the BMI does not accurately reflect body fat percentage.
- The measurement does not consider bone density, muscle mass or overall body shape.
- BMI numbers were established based off the measurements of white, non-Hispanic men. Different groups carry weight differently. The result can mean that the BMI disadvantages otherwise healthy people from other groups.
- BMI can be stigmatizing and contribute to anti-fat bias in health care settings.
- BMI does not take into consideration how fat is distributed on the body. Studies indicate that fat around the internal organs has higher health risks than fat in the arms and legs.
What other options are there besides the BMI?
The AMA recommends using other measures alongside the BMI to better address weight and obesity. Some of these other measures include:
- Relative fat mass
- Waist-to-hip ratio
- Waist-to-height ratio
- Waist circumference
Dr. Barrett says these measures, as well as focusing on a patient’s health habits, lead to better outcomes.
“I ask what kinds of foods they are eating,” she says, acknowledging the importance of whole foods. “As a general rule, we should be active most days of the week (a combination of cardio and strength). We should focus on stress management and quality sleep. In my mind, shifting the focus to these health habits will likely lead to overall improvement in mental and physical wellbeing, metabolic markers, and, subsequently, likely weight loss.”
Dr. Barrett adds, “I am very pleased and encouraged that the AMA has shifted the emphasis on solely BMI to a more whole-person approach to wellness.”