A global panel of medical experts has called for a major shift in how obesity is defined and diagnosed, arguing that the commonly used body mass index (BMI) is an inadequate measure of health.
Their recommendations, published in The Lancet Diabetes & Endocrinology, advocate for a more nuanced approach that includes assessing body fat distribution and the presence of health complications rather than relying solely on BMI.
BMI, a calculation based on a person’s height and weight, has long been used to determine whether someone is underweight, overweight, or obese. However, critics argue that BMI lacks nuance and can mislabel individuals like actor Jake Gyllenhaal and Kansas City Chiefs tight end Travis Kelce. Both men’s BMI places them in categories of “overweight” or “nearly obese,” despite their high fitness levels and low body fat percentages.
The report emphasizes that not all excess weight is harmful. For example, individuals with higher muscle mass may have elevated BMIs without facing health risks. Conversely, some people with normal BMIs might carry excess fat around critical areas, like the waist or organs, putting them at higher risk for conditions such as type 2 diabetes and heart disease.
The commission recommends a dual classification system:
- Pre-clinical Obesity: Individuals with a high BMI and excess body fat but no health complications. These individuals might be at risk for future health problems but do not yet require medical intervention.
- Clinical Obesity: Those whose weight is causing measurable health issues, such as joint pain, organ dysfunction, or metabolic abnormalities. This group would qualify for treatments like weight-loss medications.
The commission also highlighted 18 health conditions associated with obesity, ranging from breathlessness and high blood pressure to heart failure and reduced mobility.
The panel suggested incorporating additional methods to assess health risks, such as:
- Waist circumference (thresholds of 34.6 inches for women and 40 inches for men).
- Waist-to-hip or waist-to-height ratios.
- Advanced imaging techniques like DEXA scans to measure body fat distribution.
The proposed changes could influence access to expensive weight-loss medications, such as Wegovy and Zepbound. Currently, many insurers use BMI as a primary criterion for coverage. Incorporating other health indicators could help prioritize those most in need of treatment but might also limit coverage for those without immediate health issues.
Dr. Francesco Rubino, chair of the commission, emphasized that obesity should be viewed as a complex condition rather than a single number.
“It’s not just about weight—it’s about health,” he said.
Obesity specialists welcomed the new framework, saying it could reduce stigma and lead to more personalized care.
“Obesity continues to be viewed as a character flaw rather than a complex health condition,” said Rebecca Puhl, deputy director of the Rudd Center for Food Policy and Health.
However, some advocates worry that labeling more individuals with pre-clinical obesity might reinforce negative stereotypes. Tigress Osborn, executive director of the National Association to Advance Fat Acceptance, argued for individualized care rather than broad categorizations.
Despite its potential benefits, implementing the new framework poses challenges. BMI is widely used due to its simplicity, while alternatives like waist measurements or body fat scans require additional training and equipment.
Dr. David Nathan of Harvard Medical School cautioned against waiting for complications to arise before treating obesity.
“Just as you wouldn’t wait for a stroke to treat hypertension, you shouldn’t wait for obesity-related complications to intervene,” he said.
The commission’s recommendations have been endorsed by 76 organizations worldwide, including the American Heart Association.
