(2025-01-16) New Obesity Definition Shifts Focus From BMI

New Obesity Definition Shifts Focus From BMI. But the risk to health and wellbeing is not determined by weight – and therefore BMI – alone. We've been part of a global collaboration that has spent the past two years discussing how this should change. Today we publish how we think obesity should be defined and why.

The risk of ill health depends on the relative percentage of fat, bone and muscle making up a person's body weight, as well as where the fat is distributed.

People who carry their excess fatty tissue around their waist are at greatest risk of the health problems associated with obesity.

The goal of the Lancet Diabetes & Endocrinology Commission on the Definition and Diagnosis of Clinical Obesity was to develop an approach to this definition and diagnosis. The commission, established in 2022 and led from King's College London, has brought together 56 experts on aspects of obesity, including people with lived experience.

We define two categories of obesity based on objective signs and symptoms of poor health due to excess body fat.

• 1. Clinical obesity: A person with clinical obesity has signs and symptoms of ongoing organ dysfunction and/or difficulty with day-to-day activities of daily living (such as bathing, going to the toilet or dressing). There are 18 diagnostic criteria for clinical obesity in adults and 13 in children and adolescents.
• 2. Pre-clinical obesity: A person with pre-clinical obesity has high levels of body fat that are not causing any illness.

These new criteria for the diagnosis of clinical obesity will need to be adopted into national and international clinical practice guidelines and a range of obesity strategies.

Lancet article and editorial: https://www.thelancet.com/commissions/clinical-obesity