Experts: improve the definition of obesity and also look at the distribution of fat over the body

There needs to be a new definition of obesity worldwide. The ratio between height and weight, expressed in BMI, alone does not provide a good diagnosis. Next to the body mass index must also include the distribution of fat over the body.

An international committee of 58 experts advises this in The Lancet Diabetes & Endocrinology. The recommendations, endorsed by 76 health organizations, could improve obesity care worldwide if countries adopt them. In the Netherlands, healthcare providers should already look at waist size and other indications such as high blood pressure.

In most countries, obesity is defined by dividing weight in kilograms by the square of body height in meters: the body mass index. A BMI of 30 or higher is considered obese for adults.

A danger of this rough indicator alone is both over- and underdiagnosis: people with excess fat around the liver and heart do not always have a high BMI. And you can also have a high BMI without being sick – many bodybuilders, for example. BMI as an obesity indicator is also based on people of European descent, while people of Asian descent with the same BMI often have a higher fat mass – and a higher risk of diseases.

Additional measurements

The experts in The Lancet suggest additional measurements for a better diagnosis: the abdominal circumference (waist) in relation to the hips and the length is one measure. There are also devices that measure fat distribution over the body. With a BMI of 40 or more, you can speak of obesity without additional measurements, they write. With a better definition, obesity could be called a disease, rather than just a precursor to disease.

The committee also advocates two categories: ‘clinical obesity’ is a condition associated with increased blood pressure, joint pain or difficulty with daily activities such as dressing – to name a few signs and symptoms. With ‘preclinical obesity’ someone has excess fat, but the organs still function properly. In the Netherlands, a BMI lower than 30 with a large waist circumference or complaints related to being overweight is now also sufficient for treatment, just as in advice from The Lancet. But the correct diagnosis is often missed.

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Science has long established that obesity is a disease. “But receiving formal recognition from governments is sometimes quite a challenge,” says Erasmus MC professor and internist Liesbeth van Rossum. She is involved in tackling obesity in the Netherlands and Europe. “Not only are treatments not always reimbursed everywhere, obesity is also often seen as a simple weight or behavioral problem.”

Since 2008, a distinction has been made in the Netherlands between overweight (risk of disease) and obesity (disease). “We also take different ethnic backgrounds into account here,” says Jutka Halberstad, who specializes in childhood obesity, including at the Vrije Universiteit Amsterdam. She thinks it is good that the Dutch treatment guideline is in line with the Lancet advice. Although in practice, abdominal circumference and fat are still too often not measured, according to Van Rossum.

Lots of controversy

The committee still notes a lot of controversy in the medical world. According to some, those who view obesity as a disease deny individual responsibility and encourage unhealthy behavior. Others say that differences between people with a lot of body fat are too great to call obesity a disease. That is precisely why the committee draws up clinical criteria. The lack of this hinders the recognition of obesity as a disease and that does not benefit healthcare.

The experts emphasize that prejudices hinder people with obesity and their practitioners. Not only personal choices, but also genes, biological mechanisms and an unhealthy environment are decisive in the development of obesity. Stigmas, including in people themselves, can set in motion a vicious circle that causes people to avoid care and actually gain more weight.

There is a difference between determining obesity in individuals and measuring obesity in the population. Only BMI now counts in statistics. More than a billion people worldwide are obese (BMI from 30), in the Netherlands this is 16 percent. More than half of adults are overweight (from 25). In 2050 this is expected to be 64 percent.




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