For decades, Body Mass Index (BMI) has been the standard metric for assessing obesity. However, a team of 58 international researchers argues it's time for a change. Their recent recommendations, published in The Lancet Diabetes & Endocrinology, suggest a more nuanced approach that considers not just weight and height, but also the impact of excess body fat on organ function.

Lead author Francesco Rubino, chair of bariatric and metabolic surgery at King’s College London, emphasizes that obesity isn't a single entity, but rather a spectrum. He points out that BMI alone can't determine whether someone has a disease related to excess weight. The researchers propose differentiating between "preclinical" and "clinical" obesity.

Preclinical obesity signifies excess body fat without noticeable organ dysfunction, but with a heightened risk of developing conditions like type 2 diabetes, heart disease, and certain cancers. Clinical obesity, on the other hand, is defined as a chronic illness where excess body fat has negatively impacted tissue and organ function, potentially leading to severe complications like heart attack, stroke, or kidney failure.

This new framework suggests measuring adiposity—the amount of excess body fat—through methods like waist circumference measurements or body scans, in addition to BMI. Rubino stresses the need for clinicians to conduct thorough assessments to determine if an elevated BMI is due to excess fat or other factors like increased muscle mass. He also highlights the importance of evaluating organ function in individuals with confirmed obesity to identify any potential damage caused by excess adiposity.

Dr. Brett Osborn, a neurosurgeon and longevity expert, echoes the sentiment that BMI is an outdated metric. He advocates for evaluating metabolic dysfunction through markers like inflammation, insulin resistance, and glucose tolerance. Osborn points out that relying solely on BMI can misclassify muscular individuals as obese while overlooking potentially harmful visceral fat in those with a “normal” BMI. In his own practice, he utilizes measures like visceral fat scores, skeletal muscle mass, and body fat percentage for a more comprehensive assessment.

This shift in perspective emphasizes a move towards personalized care for individuals with obesity, recognizing the complex interplay of factors contributing to the condition.