BMI a poor metric for measuring people’s health, say experts

October 27, 2022 – Clinicians should pull back on the widespread use of body mass index (BMI) as a metric for assessing people’s health because it can lead to patient distrust and delayed care, say some health experts.

According to an October 24 article in the Montreal Gazette, criticism is growing that BMI—a formula that uses height and weight to measure body fat—is a “flawed, crude, archaic and overrated proxy for health.” Those opposed to its continued use argue that it was developed based on white males and has little validity for other racial and ethnic groups, and that it is sometimes used to deny certain people joint replacements and other surgeries. Experts have also pointed out that BMI fails to take into account factors such as how much fat versus muscle a patient has, the distribution of fat in their body (typically, fat around the waist increases disease risk more than fat in other places), and their metabolic health.

Among those quoted in the article was Bryn Austin, professor in the Department of Social and Behavioral Sciences at Harvard T.H. Chan School of Public Health and director of the Strategic Training Initiative for the Prevention of Eating Disorders (STRIPED).

The article cited an October 19 MedPage Today piece she co-authored urging that BMI be dropped as a clinical metric and citing a growing body of research showing the negative consequences of its use. For example, weight-based shame may lead some patients to delay or avoid medical care. If clinicians focus too much on BMI, it can introduce mistrust into the doctor-patient relationship and lead patients to opt not to follow their doctor’s advice. Further, doctors may miss diagnoses because they wrongly assume someone’s complaints or symptoms are due to weight.

Austin and co-author Tracy Richmond of Harvard Medical School noted that, “in many of the instances in which BMI is assessed in medical settings, the information is not pertinent to medical decision making and often not even used. Thus, BMI assessment may be causing risk (e.g. loss of trust, delayed care) while providing minimal to no benefit. This raises a reasonable question: What purpose is served by continued collection of these data even as the very practice of BMI assessment itself negatively affects healthcare access and quality of care?”

Read the Montreal Gazette article: ‘BMI is trash’: Why so many doctors say it’s time to ditch body mass index

Read the Medpage Today article: It’s Time to Retire BMI as a Clinical Metric