New obesity benchmark adds body fat, organ health to BMI
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The BMI, a weight-to-height ratio, has long been criticised as too simplistic as it cannot distinguish between fat and muscle mass.
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LONDON – Medical experts proposed a radical overhaul of how obesity is diagnosed, moving away from relying on body mass alone and adding broader measurements such as heart health.
The recommendation signals a long-awaited shift from a single imperfect metric towards a more personalised diagnosis that takes into account a person’s ability to accomplish everyday tasks and the state of his or her organs. It may also limit the prescription of blockbuster weight-loss drugs.
The Lancet Diabetes & Endocrinology Commission, consisting of experts from around the world, put forward the new definition for obesity on Jan 14. It was endorsed by 76 organisations, including the World Obesity Federation, the American Heart Association and Britain’s Royal College of Physicians.
“The commission is reframing obesity and acknowledges the nuanced reality of obesity,” said Dr Robert Eckel, emeritus professor of medicine at the University of Colorado Anschutz Medical Campus and one of the group’s members.
The body mass index (BMI), a weight-to-height ratio, has long been criticised as too simplistic,
Heart and lungs
A new generation of obesity drugs – such as Novo Nordisk A/S’ Wegovy and Eli Lilly and Company’s Zepbound – is changing the perception of obesity as a multifaceted illness that requires medical intervention rather than greater willpower, ushering in a revolution with ripple effects from food manufacturing to medical insurance.
The commission is “laying bare the flawed assumption that body mass for size is, by itself, a marker of health”, said Dr Adam Collins, an associate professor of nutrition at the University of Surrey who was not involved in the work.
BMI is more useful on a population level rather than an individual one, according to Dr Francesco Rubino, commission chair and head of metabolic and bariatric surgery at King’s College London.
“BMI contains no information about the functioning of organs,” he said. “For instance, how well is the heart functioning? Are the lungs doing their job as normal?”
Under the new guidelines, patients whose BMI previously classed them as obese should get checked for excess fat with tools such as waist circumference and waist-to-hip ratio. If they have excess fat, the doctor should look for signs of organ dysfunction or limitations in day-to-day activities.
A person will be considered as clinically obese only if those last measurements are also positive. Otherwise, they will be classed as having pre-clinical obesity.
The new benchmark should be included in clinical-practice guidelines and in the training of healthcare workers, according to the Lancet commission. It applies to adults regardless of age, gender or ethnicity, said the University of Colorado’s Dr Eckel.
Big Pharma impact
The new framework could help clinicians determine whether a patient needs medicines or just monitoring and general health advice. It may also, as a result, impact how obesity drugs are prescribed.
Wegovy and Zepbound are approved in the US for anyone with a BMI of 30 or more. The threshold is 27 for individuals with a weight-related condition like high blood pressure or sleep apnoea. But under a new set of rules, some patients who were previously considered obese may no longer qualify for the treatments.
Drugmakers are also increasingly looking at the importance of body composition, with companies trying to create therapies that help people keep muscle even as they shed fat. BLOOMBERG
