A New Definition of Obesity

To diagnose obesity, medical professionals primarily rely on body mass index (BMI), a calculation that estimates the percentage of body fat based on a ratio comparing height to weight. Seeking a more nuanced and precise approach, The Lancet Diabetes & Endocrinology assembled a commission comprised of 56 leading experts from various disciplines, including nutrition, endocrinology, internal medicine and public health, to reevaluate the definition and measurement of obesity.

The commission found that BMI tends to both underestimate and overestimate obesity. For instance, individuals that are stocky and muscular may be erroneously classified as obese due to the weight of muscle tissue, while those with low muscle mass but excess abdominal fat around their organs may not be considered obese.

The commission recommends a revised definition of obesity that emphasizes excess body fat accumulation around the waist, measuring waist circumference, waist-to-hip ratio or waist-to-height ratio, in conjunction with BMI. Alternatively, a dual-energy X-ray absorptiometry (DEXA) scan can be employed to directly measure body fat using low-radiation X-ray capabilities at a higher cost.

In an interview with NPR News, Dr. Robert Kushner, a member of the commission, explained the significance of abdominal fat, stating, “Fat in the belly causes systemic inflammation, which then goes on and causes other metabolic problems like elevated blood sugar, elevated blood pressure and increased fats in the blood.”

The commission also recommended making a distinction between preclinical and clinical obesity. Individuals with clinical obesity would exhibit diminished organ or tissue function due to obesity or substantial mobility limitations. Consequently, they would receive appropriate treatments for their condition. Individuals with preclinical obesity would undergo health counseling and monitoring to reduce the risk of developing clinical obesity