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BMI: A Flawed Measure of Health

It’s time we move beyond BMI and adopt a holistic approach to truly gauge health.

Body Mass Index (BMI) has long been regarded as a standard measure for assessing weight-related health risks and, more recently, determining eligibility for anti-obesity medications like GLP-1 receptor agonists semaglutide (Wegovy) and tirzepatide (Zepbound), according to the FDA. 

BMI, calculated from weight and height, offers a simplistic yet flawed assessment of health. It was initially designed for non-Hispanic white populations and overlooks nuances like muscle mass, fat distribution, and ethnic background, which can influence certain risk factors. It’s an antiquated measure that perpetuates inequities in healthcare and misses the mark for calculating cardiometabolic conditions.

The perception that a “normal” BMI is ideal and an “overweight to obese” BMI is not ideal only exacerbates bias within the medical community and complicates our efforts to solve the obesity crisis. Individuals with an overweight to obese BMI that is, > 25 and>30, respectively, may be healthy. At the same time, those within the “normal” BMI range may not be. They could have excess visceral fat (the dangerous type that sits around the organs) and the associated health risks. Moreover, as people age, their expected fat accumulation further complicates BMI’s reliability. We can’t judge health based solely on BMI.

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Recognizing these limitations, the American Medical Association (AMA) acknowledged in June 2023 that BMI is an imperfect measure and that measuring waist circumference in addition to BMI may be a better way to predict weight-related risk. 

While BMI may be suitable as a population health measure, it doesn’t work well at the individual level to determine the need for drastic — and expensive — interventions like GLP-1s for weight loss.

AOM prescribing and cardiovascular risk

With the rising popularity of GLP1s for weight loss, we’ve seen a surge in patients visiting their PCPs in search of prescriptions. FDA labeling for anti-obesity medications (AOMs) requires BMI criteria of >30 or >27 with at least one weight-related comorbidity to qualify for a GLP-1. This criteria may be adjusted for the Asian phenotype, who tend to accumulate higher visceral fat over subcutaneous fat.

However, GLP-1 agonists aren’t appropriate for every patient who qualifies for an AOM based on BMI criteria alone. These drugs are expensive, and they come with side effects and other risks. A recent study showed that nearly two-thirds of the people prescribed a GLP-1 receptor agonist, self-discontinued in year two. It’s obvious we’re not effectively treating obesity by simply writing prescriptions.

The recent surge in GLP-1 prescribing is expected to increase employer healthcare costs by 5.4 percent this year alone. We need to more carefully select whom we prescribe these intensive drugs if we want to reduce costs and optimize long-term success for our patients. We should look at various clinical metrics and lean on other evidence-based interventions to yield a clinically meaningful weight loss of 5-10% of total body weight. Other evidence-based interventions could include medical nutrition therapy a registered dietitian provides and other less expensive medications that can treat obesity, like Contrave, Metformin, or Topiramate, Zonisamide, Qsymia, and Orlistat.

Focusing on the maximum amount of weight loss is not the way to solve our obesity problem, nor is it the most appropriate objective when other cardiometabolic risk factors exist. Fundamentally, we should prioritize reducing cardiovascular and metabolic risk, which can often be achieved through 5-10% weight loss. 

If we want to reduce rates of hypertension, high LDL, and type 2 diabetes, we need to look closer at other measurements like blood pressure and waist circumference. Waist circumference is associated with a higher amount of visceral fat when >35 inches for women and >40 inches for men and can be a high indicator of poor metabolic health. 

Bias and stigma associated with BMI in healthcare

We also need to consider the bias and stigma created by the widely accepted assertion that BMI correlates to health. Weight bias is dangerous: The psychological stress that comes from living in a larger body and experiencing bias from and within the medical community increases the risk of depression, anxiety, substance abuse, poor body image, and missed diagnoses. In many cases, physicians are prone to anti-obesity bias, which can lead them to dismiss the medical concerns of someone who is living with obesity. 

We need to take a more nuanced view of how BMI varies across populations, ethnicities, and athletes when we use it as a health metric. Training clinicians to recognize inherent bias around weight stigma is crucial to moving past the idea that weight correlates to health and further that BMI is enough to determine who is unhealthy enough to get on medication.

Comprehensive, whole-person-focused treatment is the solution

It’s time we move beyond BMI and adopt a holistic approach to truly gauge health. That may look like measuring blood pressure, LDL cholesterol, and A1C, alongside factors like body composition, metabolic health, and mental health before determining the right interventions. 

Integrated, personalized treatment that goes beyond weight and addresses mental and physical health should be the gold standard for determining who gets a GLP-1. Helping patients heal from the trauma, bias, and stigma that they may have encountered requires a compassionate and empathetic approach. Clinicians trained in cognitive behavioral techniques can help patients foster a positive relationship with food and body while also screening and triaging to therapy when other more complex mental health conditions are present.  Further, clinicians must undergo ongoing training to recognize and mitigate weight bias, fostering an environment of inclusivity and equitable care.

Successful treatment requires interdisciplinary collaboration, integrating medical, nutrition therapy, and psychological interventions tailored to individual needs. Working with registered dietitians to optimize nutrition, focus on food quality versus just quantity and calories, and achieve an ideal and realistic body weight is crucial. Eating the right foods and optimizing nutrition when only small meals are tolerated is crucial to overall health and the prevention of rapid weight and lean body mass loss. 

Conclusion

BMI’s shortcomings as a health measure necessitate a paradigm shift in healthcare practices. Overprescribing GLP-1 based on BMI criteria alone overlooks crucial aspects of individual health and perpetuates inequities within healthcare. Moving forward, we must embrace more comprehensive, personalized treatment strategies that transcend BMI and address holistic health factors. We can ensure equitable healthcare access and improved patient outcomes by prioritizing inclusivity, empathy, and evidence-based practices.

Photo: aykut karahan, Getty Images

Gretchen Zimmermann is VP of Clinical Strategy at Vida Health.

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