Global report recommends more precise definition of obesity than BMI

There is a risk that too many people are being diagnosed as obese when a “more precise” and “nuanced” definition is needed, a report from global experts said.

Doctors should consider the general health of patients with excess fat, rather than just measuring their body mass index (BMI), it says.

Those who suffer from chronic diseases caused by their weight should be diagnosed with “clinical obesity”, while those who have no health problems should be diagnosed with “preclinical obesity”.

It is estimated that more than a billion people live with obesity worldwide and prescription weight loss medications are in high demand.

The report, published in the journal The Lancet Diabetes & Endocrinology, is supported by more than 50 medical experts from around the world.

“Obesity is a spectrum,” says Professor Francesco Rubino, of King’s College London, who chaired the group.

“Some people have it and manage to live a normal life, to function normally.

“Others cannot walk or breathe well, or are in wheelchairs with significant health problems.”

The report calls for a “reframing” of obesity to distinguish between patients with disease and those who remain healthy but are at risk of disease in the future.

Currently, in many countries, obesity is defined as having a BMI greater than 30 – a measurement that estimates body fat based on height and weight.

Access to weight loss drugs such as Wegovy and Mounjaro is often reserved for patients in this category.

In many parts of the UK, the NHS also requires people to have a weight-related health problem.

But BMI reveals nothing about a patient’s overall health, the report says, and fails to distinguish between muscle and body fat, nor to account for the more dangerous fat around size and organs.

Experts argue for new model that examines signs of obesity affecting body organs – such as heart disease, shortness of breath, type 2 diabetes or joint pain – and their detrimental impact on life daily.

This indicates that obesity has become a clinical disease and requires drug treatment.

However, people with ‘preclinical obesity’ should receive weight loss advice, counseling and monitoring, rather than resorting to medication and surgery, to reduce the risk of development of health problems. Treatment may also be necessary.

“Obesity is a health risk. The difference is that for some it is also a disease,” Professor Rubino said.

It made sense to redefine it, he added, to understand the level of risk in a broad population, instead of the current “fuzzy picture of obesity.”

The waist-to-height ratio or direct measurement of fat, along with a detailed medical history, can give a much clearer picture than BMI, the report says.

Childhood obesity expert Professor Louise Baur, from the University of Sydney, who contributed to the report, said the new approach would allow obese adults and children to “receive more appropriate care”, while reducing the number of overdiagnoses and unnecessary treatments. .

At a time when drugs reducing body weight by up to 20% are prescribed on a large scale, the report estimates that this “reframing” of obesity “is all the more relevant” as it “improves the precision of diagnosis”.

The Royal College of Physicians said the report laid a strong foundation “for treating obesity with the same medical rigor and compassion as other chronic conditions”.

Distinguishing between preclinical and clinical obesity would be “a vital step forward” and would “highlight the need for early identification and intervention” while providing appropriate care to patients whose health was already seriously affected, the university said.

But some fear that pressure on health budgets could mean less money for people in the “pre-obese” category.

Professor Sir Jim Mann, co-director of the Edgar Diabetes and Obesity Research Centre, in Otago, New Zealand, said the focus would likely be “on the needs of those who are defined as clinically obese”. and that the limited funding was “very likely” to be directed to them.