New obesity diagnosis plan: moving beyond BMI for more accurate treatment

Experts propose new obesity diagnosis, combining BMI, waist size, and health issues.

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A group of global experts has proposed a new approach to defining and diagnosing obesity, reducing the reliance on the controversial body mass index (BMI) and aiming to better identify individuals in need of treatment for the disease associated with excess body fat.

The new recommendations, released on Tuesday, suggest that obesity should no longer be defined solely by BMI, a calculation based on height and weight. nstead, the definition would incorporate additional measurements, such as waist circumference, alongside evidence of health problems linked to excess body fat.

Currently, in the United States, approximately 40% of adults are affected by obesity, according to the US Centers for Disease Control and Prevention (CDC).

Dr. David Cummings, an obesity expert at the University of Washington and one of the 58 authors of the report published in The Lancet Diabetes & Endocrinology journal, emphasized the goal of improving the precision of obesity diagnosis to better target those who require medical intervention.

The report introduces two new diagnostic categories: clinical obesity and pre-clinical obesity. Clinical obesity refers to individuals who meet BMI criteria, along with other markers of obesity, and have evidence of organ or tissue damage caused by excess weight.

This could include conditions such as heart disease, high blood pressure, or chronic joint pain. These individuals would be eligible for treatments, including dietary interventions and obesity medications.

Pre-clinical obesity, on the other hand, applies to individuals at risk for obesity-related health conditions but who do not yet show evidence of ongoing illness.

The new criteria aim to distinguish between those with clinically significant excess fat and those without immediate health consequences.

BMI has long been criticized for its limitations, as it can either over-diagnose or underdiagnose obesity. For example, individuals with high muscle mass, such as athletes, may have a high BMI despite having normal fat levels.

The new criteria would better capture those with excess fat who do not necessarily have a BMI above 30, which is the current threshold for obesity.

Preliminary analysis of the new definition suggests that about 20% of individuals previously classified as obese would no longer meet the new criteria, while approximately 20% of individuals with lower BMI but significant health effects would now be classified as clinically obese.

However, experts indicate that the overall percentage of individuals diagnosed with obesity would not dramatically change.

The new definitions have been endorsed by over 75 medical organizations globally, though it remains unclear how quickly they will be adopted in practice.

The report acknowledges that implementing these changes will involve significant costs and workforce considerations.

Challenges to adoption include practical concerns, such as varying protocols for measuring waist circumference and the need for comprehensive health assessments and lab tests to differentiate between clinical and pre-clinical obesity.

Dr. Katherine Saunders, an obesity expert at Weill Cornell Medicine, noted that for the new classification system to be widely adopted, it would need to be cost-effective, quick, and reliable.

Some experts, like nutritionist Kate Bauer from the University of Michigan, have expressed concerns that the new classification system may confuse the public, who generally prefer simple health messages.

Dr. Robert Kushner, an obesity expert at the Northwestern Feinberg School of Medicine and a co-author of the report, acknowledged that overhauling the definition of obesity will be a gradual process. "This is the first step in the process," he said, adding that it would spark important conversations about redefining obesity care.