"The term 'clinical obesity' should be used for patients with a medical condition caused by their weight, while 'pre-clinically obese' should be applied to those remaining fat but fit although at risk of disease.
This approach is better for patients than relying only on body mass index (BMI) to determine obesity. The report, published in The Lancet Diabetes & Endocrinology journal, is supported by more than 50 medical experts worldwide.
"Some individuals with obesity can maintain normal organ function and overall health, even long term, whereas others display signs and symptoms of severe illness here and now," stated Prof Francesco Rubino, from King's College London, who led the expert group. "Obesity is a spectrum," he added.
The current definition of obesity means many individuals are being diagnosed as obese but not receiving the most appropriate care, the report explains. BMI is calculated by dividing weight in kilograms by height in meters squared but has limitations. It measures weight but not fat, leading to misconceptions for very muscular individuals.
BMI is useful at a population level to assess weight categories but lacks detail on an individual's health status. Waist measurement, body fat analysis, and medical history provide a clearer health picture than BMI alone.
"Obesity is a health risk - the difference is it's also an illness for some," Prof Rubino highlighted.
When obesity is a disease, there will be evident signs of organ impact, and treatment may involve drugs or surgery. In the pre-clinical stage, weight-loss advice and monitoring are key to prevent health issues.
Redefining obesity can improve accurate diagnosis, especially with the availability of weight-loss drugs like Wegovy and Mounjaro. Children and adults with obesity can benefit from more appropriate care, reducing over-diagnosis and unnecessary treatments.
The approach recommended in the report lays a robust foundation for treating obesity as rigorously as other chronic illnesses. Concerns, however, exist regarding budget constraints affecting patients in the pre-obesity category."