Several doctors have called for a ‘radical overhaul’ of how obesity is defined amid concerns that body mass index (BMI) may be causing millions of people to be misdiagnosed.
According to a report in the Lancet Diabetes and Endocrinology Journal, doctors have expressed concern that BMI may be an ‘ineffective’ measure of obesity because it is not a direct measure of fat and does not provide information about a person’s health.
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Professor Francesco Rubino, chair of the Lancet commission which produced the report, said that ‘obesity is a spectrum,’ and reframing it would help to capture the ‘nuanced reality of obesity’.
‘Considering obesity only as a risk factor, and never a disease, can unfairly deny access to time-sensitive care among people who are experiencing ill health due to obesity alone. On the other hand, a blanket definition of obesity as a disease can result in overdiagnosis and unwarranted use of medications and surgical procedures, with potential harm to the individual and staggering costs for society.’
According to the commission, more than a billion people are living with obesity, diagnosed using a person’s BMI to estimate the amount of excess fat in their body. A BMI is the ratio of a person’s height to weight and in most countries a number over 30 indicates obesity.
However, the report argues that BMI does not distinguish between muscle and body fat or account for more dangerous fat around the organs. Doctors noted that some people with excess body fat do not have a high BMI. At the same time, others with a high BMI are diagnosed with obesity despite maintaining normal organ and bodily functions.
The proposed reframing of obesity, endorsed by more than 75 medical organisations, has called for different measures in addition to BMI. This includes calculating waist-to-hip and waist-to-height rations and looking at objective symptoms of obesity-related illnesses such as heart disease, type 2 diabetes and join pains.
Doctors recommended two categories of obesity. People living with chronic illness caused because of their weight would be diagnosed with clinical obesity and receive appropriate management and treatments, including weight-loss drugs. Whereas people with no ongoing illness but with an increased risk of developing obesity or related diseases will be diagnosed with pre-clinical obesity and be supported to reduce the risks.
The Royal College of Physicians welcomed the report as a strong foundation for treating obesity.
Dr Kath McCullough, a special adviser on obesity, 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.’