Beyond BMI: New framework for obesity diagnosis prioritizes overall health

The system for diagnosing and managing obesity can no longer be about just body mass index (BMI), which is excluding many people who would benefit from obesity treatment. A new framework for the diagnosis, staging and management of obesity in adults, launched today by the European Association for the Study of Obesity (EASO) and published in Nature Medicine, will propose modernizing obesity diagnosis and treatment to take account of all the latest developments in the field, including the new generation of obesity medications.

Despite the wide recognition of obesity as a multifactorial, chronic, relapsing, non-communicable disease marked by an abnormal and/or excessive accumulation of body fat - in many settings, the diagnosis of obesity is still based solely on BMI cut-off values, and does not reflect the role of adipose tissue distribution and function in the severity of the disease.

The EASO Steering Group, comprised of experts including current and former Association Presidents, have put together a series of statements on obesity diagnosis, staging and treatment that will move management of the condition in line with the latest scientific knowledge and developments.

The authors say: "An important novelty of our framework regards the anthropometric component of the diagnosis. The basis for this change is the recognition that BMI alone is insufficient as a diagnostic criterion, and that body fat distribution has a substantial effect on health. More specifically, the accumulation of abdominal fat is associated with an increased risk of developing cardiometabolic complications and is a stronger determinant of disease development than BMI, even in individuals with a BMI level below the standard cut-off values for obesity diagnosis (BMI of 30)."

The new framework makes explicit that abdominal (visceral) fat accumulation is an important risk factor for health deterioration, also in people with low BMI and still free of overt clinical manifestations; and the new framework includes people with lower BMI (≥25–30 kg/m²) but increased abdominal fat accumulation and the presence of any medical, functional or psychological impairments of complications in the definition of obesity, hence reducing the risk of undertreatment in this particular group of patients in comparison to the current BMI-based definition of obesity.

The authors make clear the pillars of treatment of people with obesity in their recommendations substantially adhere to current available guidelines. Behavioural modifications, including nutritional therapy, physical activity, stress reduction and sleep improvement, were agreed as main cornerstones of obesity management, with the possible addition of psychological therapy, obesity medications and metabolic or bariatric (surgical and endoscopic) procedures.

However, for the latter two options, the steering committee discussed the fact that current guidelines are based on clinical evidence derived from clinical trials, in which inclusion criteria were mostly based on anthropometric cut-off values rather than on a complete clinical evaluation. In current practice, the strict application of these evidence-based criteria precludes the use of obesity medications or metabolic/bariatric procedures in patients with a substantial burden of obesity disease but low BMI values.

Therefore, members of the steering committee proposed that, in particular, the use of obesity medications should be considered in patients with BMI of 25 kg/m² or higher and a waist-to-height ratio of above 0.5 and the presence of medical, functional or psychological impairments or complications, independently from current BMI cut-off values.

The authors say: "This statement may also be seen as a call to pharmacological companies and regulatory authorities to use inclusion criteria that are more adherent to the clinical staging of obesity and less to traditional BMI cut-offs when designing future clinical trials with obesity medications."

They conclude: "This statement will move obesity management closer to the management of other non-communicable chronic diseases, in which the goal is not represented by short-term intermediate outcomes, but by long-term health benefits. Defining long-term personalized therapeutic goals should inform the discussion with the patients from the beginning of the treatment, considering the stage and severity of the disease, the available therapeutic options and possible concomitant side effects and risks, patient preferences, individual drivers of obesity and possible barriers to treatment. Emphasis on the need for a long-term or life-long comprehensive treatment plan rather than short-term body weight reduction is warranted."