A group of global experts propose a new way to identify and diagnose obesity, reducing the focus on the controversial BMI, and hope to better identify people who need treatment for the disease caused by excess body fat.
Under the recommendations released Tuesday evening, obesity will not be defined solely by the body mass index, which is a calculation of height and weight, but will be combined with other measurements, such as waist circumference, as well as evidence of health problems associated with excess weight.
It is estimated that obesity affects more than one billion people worldwide. In the United States, about 40% of adults are obese, according to the US Centers for Disease Control and Prevention.
“The whole goal of this is to get a more precise definition so we can target the people who need help the most,” said Dr. David Cummings, an obesity expert at the University of Washington and one of the study’s 58 authors. Report published in Lancet Diabetes and Endocrinology.
The report introduces two new diagnostic categories: clinical obesity and preclinical obesity.
People with clinical obesity reach BMI and other signs of obesity and have evidence of organ, tissue, or other problems caused by excess weight. This can include heart disease, high blood pressure, liver or kidney disease, or severe chronic pain in the knee or hip. These people will be eligible for treatments, including diet and exercise interventions and obesity medications.
The report says people with preclinical obesity are at risk of developing these conditions, but do not have ongoing disease.
BMI has long been considered a flawed measure that can over- or under-diagnose obesity, which is currently defined as a BMI of 30 or greater. But the report notes that people with excess body fat don’t always have a BMI higher than 30. And people with high muscle mass — football players or other athletes — may have a high BMI despite their fat mass. Natural.
Under the new criteria, about 20% of people who were once classified as obese no longer meet that definition, the preliminary analysis suggests. About 20% of people who suffer serious health effects but have a low BMI are now considered clinically obese, experts said.
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“It won’t significantly change the percentage of people who are defined as obese, but it will better diagnose people who actually have clinically significant excess fat,” Cummings said.
The new definitions have been approved by more than 75 medical organizations around the world, but it is not clear how widespread or quickly they will be adopted in practice. The report acknowledges that implementing the recommendations “will incur significant costs and implications for the workforce.”
“It is too early at this point to gauge how plans will incorporate these criteria into other coverage or policies,” said a spokesman for the health insurance trade group AHIP, formerly known as America’s Health Insurance Plans.
There are practical issues to consider, said Dr. Katherine Saunders, an obesity expert at Weill Cornell Medical College and co-founder of obesity treatment company FlyteHealth. Measuring waist circumference may seem simple, but protocols vary, many doctors are not thoroughly trained, and standard medical tape measurements are not large enough for many people with obesity.
Additionally, determining the difference between clinical and preclinical obesity requires a comprehensive health assessment and laboratory testing.
“For a new classification system to be widely adopted, it needs to be very fast, inexpensive and reliable,” she said.
Kate Power, a nutrition expert at the University of Michigan School of Public Health, said the new definitions are likely to be confusing.
“The public loves and needs simple messages. I don’t think this differentiation will change anything,” she said.
Dr. Robert Kushner, an obesity expert at Northwestern University Feinberg School of Medicine and co-author of the report, acknowledged that reforming the definition of obesity will take time.
“This is the first step in this process,” he added. “I think it will start the conversation.”
& Edition 2025 The Canadian Press
