The modern definition of obesity challenges the current apply of BMI

Obesity should be assessed beyond the standard measure of body mass index, or BMI, under a modern definition of the condition published by an international commission.

His reportpublished Tuesday in The Lancet Diabetes & Endocrinology journal, justifies focusing on the amount of body fat and medical complications a person has, rather than just their weight.

If the guidelines are widely adopted, they could change doctors’ perceptions about who should be treated for obesity. They may also affect the apply of prescription drugs used to treat obesity, such as Wegovy and Zepbound. The modern definition of obesity was supported by 76 organizations around the world.

The Commission proposed that instead of continuing to apply the BMI index as a way of defining obesity, it should become a screening tool to determine who should be tested for excess body fat.

The commission said people who have a BMI over 25 and too much body fat, but are otherwise hearty, should basically be left alone. They should be monitored and advised to ensure that they do not gain and possibly lose weight.

Their condition could be called preclinical obesity.

Other people with any of the 18 obesity-related diseases – 13 among children and adolescents – require treatment to improve their health and prevent stern organ damage. These conditions include shortness of breath, heart failure, hip or knee pain, metabolic disorders and poorly functioning organs.

Their condition could be called clinical obesity.

The group concluded that people with a BMI of 40 or more are clinically obese based on BMI alone – there is no need to assess their body fat.

The committee said it had no knowledge of the prevalence of either type of obesity.

According to the group, the easiest way for doctors to check whether a person has excess body fat is to wrap a tape measure around the waist. If a woman’s waist is over 34.6 inches, she most likely has too much fat. For a man, the waist threshold will be at least 40 inches.

Other tools for healthcare professionals include waist-to-hip ratio, waist-to-height ratio, or DEXA scans, a type of X-ray.

The committee’s 58 experts worked on the report for years, meeting regularly online. Instead of thinking about obesity as a disease, they wanted to assess it in a different way, said the committee’s chairman, Dr. Francesco Rubino, a bariatric surgeon at King’s College London. (Dr. Rubino consults with developers of drugs and medical devices for obesity.)

The committee’s approach is consistent with that of the American Heart Association, which endorsed the report.

“We have struggled with imprecise methods for defining abnormal weight,” said Dr. Mariell Jessup, the association’s scientific and medical director. “How do you define ideal weight and how do you define unhealthy weight?”

“We have been asked many times: Do you think obesity is a chronic disease? We weren’t comfortable saying yes or no,’ she said. “We think it’s more refined.”

Rebecca Puhl, deputy director of the Rudd Center for Food Policy and Health at the University of Connecticut, said she saw the commission’s approach as “an attempt to reduce some misconceptions about obesity that have the potential to reduce stigma.”

“Obesity is still seen as a character flaw rather than a convoluted health condition,” she said.

However, it may be hard to bring modern definitions into common apply.

For years, experts have complained about the reliance on BMI to determine overweight and obesity.

The indicator is straightforward to measure – all you need is a person’s height and weight. It soon became the standard for determining whether a person was underweight, overweight or obese.

BMI has been identified as a major risk factor for diabetes, heart disease, cancer and other conditions, said Dr. David M. Nathan, a professor of medicine at Harvard and founder of the diabetes center at Massachusetts General Hospital.

He added that a huge waist is also a risk factor. However, unlike BMI, waist measurements are often taken incorrectly in medical settings.

Dr. Nathan said it’s “unrealistic to say the whole world will change for this.”

It is equally unrealistic, he continued, to say that obesity should not be treated until complications appear. “In my opinion, hypertension is not treated until the person has had a stroke,” Dr. Nathan said.

While not every obese person develops stern health problems, “the number of people who do not experience any weight-related complications is quite tiny,” Dr. Nathan added.

The apply of the modern standard may also have consequences for modern anti-obesity drugs and other drugs introduced to the market. They are so steep that some health systems that initially covered them for people with obesity – defined by their BMI – have decided they can no longer afford them.

But Dr. David Cummings, a committee member and obesity expert at the University of Washington, suggested they could be narrow to patients diagnosed with clinical obesity.

This group’s needs, he said, “are more compelling.”