Using the Body Mass Index (BMI) one can estimate the body fat percentage. The weight-to-height ratio is calculated using a statistical method based on the gender assigned at birth.
It has been known since its development by Adolphe Quetelet almost a century ago that BMI helps identify obese people at a public health level.
Recently, however, it has been challenged for its discrepancies. In historically marginalized ethnic groups, such as Black women, BMI may misclassify rates of overweight and obesity.
This article examines the history of BMI, whether it discriminates against Black women, and how to use other metrics to gauge an individual’s health status.
Does BMI discriminate against Black women?
Given that the BMI was designed primarily on studies in white populations, its capacity to effectively define overweight and obesity in other populations has been questioned (5Trusted Source) (5Trusted Source).
Furthermore, BMI has been altered to compare “healthy” and “unhealthy” weights. High BMI bodies have been stigmatized as “diseased bodies” in both scientific literature and public messages.
Furthermore, persons with high BMI bodies have been labeled as lacking willpower. For people and populations that BMI misclassifies as overweight, there might be social and medical ramifications.
African American BMI Chart
Factors that the BMI fails to consider
Women BMI Chart:
Underweight = 18.5
Normal weight = 18.5–24.9
Overweight = 25–29.9
Obesity = BMI of 30 or greater
BMI is an index connecting weight to height. Despite being an estimate of body fat, it does not take body composition into account — that is, the proportion of weight that’s fat vs lean mass, like a muscle (5Trusted Source) (5Trusted Source).
For instance, athletes or those with higher muscle mass percentages are often incorrectly categorized as overweight because of BMI measurements, but their body fat % may be within normal ranges (1Trusted Source) (1Trusted Source).
Generally, non-Hispanic Black men and women have lower body fat percentages and higher muscle mass compared with non-Hispanic white individuals and Mexican Americans (5Trusted Source, 6Trusted Source) (5Trusted Source, 6Trusted Source).
This suggests that the BMI index may exaggerate overweight and obesity in non-Hispanic Black men and women, and it potentially misclassifies them as “unhealthy.”
Remember: Although BMI is an excellent indication to track changes at the population level, it’s insufficient as a standalone measure to diagnose obesity in individuals (1Trusted Source, 3Trusted Source, 5Trusted Source) (1Trusted Source, 3Trusted Source, 5Trusted Source).
Is BMI administered differently to Black women and People of Color?
The BMI is used in the same way for white, Hispanic, and Black persons. However, it’s been corrected for Asian people, because it underestimates obesity in this group.
People of Asian heritage have a “normal-weight obesity” body type. This suggests that their BMI normally falls within the normal range, yet they have a greater body fat percent at any given BMI.
Therefore, the BMI scale has been lowered to account for their body type and to appropriately identify those at an elevated risk of developing type 2 diabetes, which is frequent among Asian populations.
A prior study demonstrated that ethnic disparities in the body structure of Greenland Inuit populations compared with European and American white populations indicates that the BMI likely also overestimates overweight and obesity among the Inuit.
Ethnic disparities in body composition among women of African origin may be an underlying contributor to higher BMI rates among Black women. But those variations need to be examined to understand their clinical significance.
Racism and the BMI index
A study in counties across the United States found that structural racism — discriminatory policies that lead to health disparities and poor health outcomes in some persons — impacts higher BMI in Black people.
BMI is closely associated with race. For example, white men have the lowest trajectories for weight growth, and Black women have the highest probabilities of developing obesity and higher BMIs – 6 percent greater than everyone else.
Furthermore, the BMI may be deemed intrinsically racist. Its measurements are based on a restricted study sample of white people and don’t account for changes in body composition between ethnic groups, but it’s been used to assess obesity and “health” in these groups regardless.
Racism continues to be of scientific interest for the impact it plays on health disparities, BMI among racial and ethnic groups, and disease rates