Lancet Report: Definition and diagnostic criteria of clinical obesity

What Was It?

The Lancet Commission on the Definition and Diagnosis of Clinical Obesity, made up of 56 international experts, developed this consensus statement to refine how obesity is classified. Endorsed by the World Obesity Federation and 75 other medical organisations, the statement provides clearer distinctions between pre-clinical obesity (risk stage) and clinical obesity (disease stage).

Key distinction:

• Pre-clinical obesity – Excess fat but no organ dysfunction or activity limitations.

• Clinical obesity – Excess fat with organ dysfunction or activity limitations.

Why Was It Needed?

In medicine, many conditions exist on a spectrum—think of pre-diabetes and diabetes. Obesity is no different. There has long been debate about when excess body fat is simply a risk factor versus when it becomes a disease, which has implications for risk factor modification versus medical treatment, as well as funding and access to healthcare. The consensus statement aims to align obesity classification with other medical conditions, ensuring a more precise framework for diagnosis and treatment.

What’s changing?
✔️ BMI is now only a screening tool, not a diagnostic measure.
✔️ Diagnosis can include waist circumference, waist-to-height ratio, or direct body fat measurements.
✔️ Recognition that some individuals with excess fat remain well.

Considerations for clinicians:
🔹 How to integrate new assessment criteria into practice.
🔹 Potential funding implications for pre-clinical obesity.
🔹 The challenge of balancing early intervention with avoiding overdiagnosis.

This consensus statement introduces a more detailed classification of obesity, but its real-world impact will depend on how it’s implemented in clinical settings.