Experts called for measurements beyond BMI to be considered (Image: Getty)
Experts are calling for a “radical overhaul” of the way is diagnosed which could see millions of people told they do not need to .
A major global commission concluded that current medical approaches rely too much on BMI without taking into account health or illness at an individual level.
Instead, they proposed a more nuanced approach which includes measures of body fat such as waist circumference or waist-to-hip ratio.
The new system would see people categorised as having either clinical obesity, if their weight is affecting their organ function or ability to complete day-to-day activities, or pre-clinical obesity where they do not have ongoing illness but are at increased risk of health problems.
People with pre-clinical obesity could be offered advice on how to reduce their risk level to prevent serious health problems in the future.
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But depending on their risk, some may only need counselling and monitoring over time, rather than active treatment, the commission said.
Prof Francesco Rubino, the group’s chair and an expert in metabolic and bariatric surgery at King’s College London, said adopting the proposed system would help reduce over-diagnosis of obesity in the .
He added: “Some people who are today classified as having obesity by BMI, they might be athletes, they play sports, they’re very active, they might have very strong bones.
“Saying that those people have obesity and then classifying them as having a disease would obviously be an over-diagnosis. Certainly there is already over-diagnosis happening and no system, the NHS or others, has this method yet.
“Everybody has been using the old classification for four decades at least but we are calling for a radical change because obviously in the context of one billion people being classified as having obesity in the world today and with that number projected to increase, no country is rich enough to be able to afford inaccuracy in the diagnosis of obesity.”
Prof Rubino said the long-running debate about whether obesity should be considered a disease was “flawed because it presumes an implausible all-or-nothing scenario where obesity is either always a disease or never a disease”.
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He added: “Evidence, however, shows a more nuanced reality. Some individuals with obesity can maintain normal organs’ function and overall health, even long term, whereas others display signs and symptoms of severe illness here and now.”
The commission involved 56 international experts who attended monthly meetings between June 2022 and December 2024.
Launching the report at a press conference, commissioner Professor Louise Baur, chair of child and adolescent health at the University of Sydney, gave the example of two children with similar measurements but different medical histories.
She said she would be less worried about a child whose family members “may be big but have lived a very healthy long life” than one whose parents had type 2 diabetes and premature heart disease.
Prof Baur said: “The two children may have the same body fat, the same BMI but one is at much higher risk than the other.
“That’s the sort of thing that a clinician would take into account. What’s the family history? What’s the future risk for this person?”
Describing the commission’s findings, she added: “We propose a radical overhaul of the actual diagnosis of obesity in order to improve global healthcare practices and policies.
“This nuanced approach to obesity will enable evidence-based and personalised approaches to prevention, management and treatment in adults and children living with obesity, allowing them to receive more appropriate care, proportional to their needs.
“This will also save healthcare resources by reducing the rate of over-diagnosis and unnecessary treatment.”
The commission’s report was published in The Lancet Diabetes & Endocrinology and endorsed by more than 75 medical organisations around the world.
Commenting on the findings, Dr Kath McCullough, special adviser on obesity at the Royal College of Physicians, said: “For too long, we’ve relied on BMI as a simple measure of obesity, which has often misrepresented the condition and fails to fully reflect how excess body fat impacts a person’s health.
“The commission’s distinction between pre-clinical and clinical obesity represents a vital step forward, highlighting the need to identify and intervene early while providing appropriate care to those already experiencing severe health impacts.”
The study comes after the leader of a government anti-obesity programme said that giving everyone access to weight loss drugs could “bankrupt the NHS”.
Professor Naveed Sattar, who leads the UK government’s Obesity Healthcare Goals programme, told the : “The cost of the drugs is still at a level where we cannot afford to treat several million people within the UK with these drugs. It would simply bankrupt the NHS.”