New obesity definition calls into question current use of BMI

Obesity should be assessed in ways that go beyond the standard measure of body mass index (BMI), according to a new definition of obesity published by an international committee.

the reportThe paper, published in the Lancet Diabetes and Endocrinology journal on Tuesday, argues that the focus should not just be on weight, but also on the amount of body fat and any comorbidities a person has.

If widely adopted, the guidelines could change doctors' perceptions of who needs obesity treatment. It may also affect the use of prescription drugs to treat obesity, such as Wegovy and Zepbound. The new definition of obesity was supported by 76 organizations around the world.

The committee suggested that instead of continuing to use the current BMI as a way to define obesity, it should be used as a screening tool to determine who should be tested for excess body fat.

The committee said people with a BMI over 25 who have too much fat but are otherwise healthy should be largely left alone. They should be monitored and advised not to gain more weight, and in some cases to lose weight.

Their condition is called preclinical obesity.

Other people with any of the 18 conditions caused by obesity (13 conditions for children and adolescents) need medical treatment to improve their health and prevent serious damage to their organs. I'm here. Symptoms include shortness of breath, heart failure, lower back and knee pain, metabolic abnormalities, and organ dysfunction.

Their condition is called clinical obesity.

The group said it considers people with a BMI of 40 or above to be clinically obese based on BMI alone, and there is no need to assess body fat.

The commission said the prevalence of the two types of obesity is unknown.

The group says the easiest way for doctors to determine whether a person has excess body fat is to wrap a tape measure around a person's waist. If a woman's waist is more than 34.6 inches, she may have too much fat. For men, the waist threshold is at least 40 inches.

Other tools for medical professionals include waist-to-hip ratio, waist-to-height ratio, or DEXA scan, which is a type of X-ray.

The commission's 58 experts met regularly online and spent years writing the report. The committee's chairman, Dr Francesco Rubino, a bariatric surgeon at King's College London, said that instead of thinking of obesity as a disease, they wanted to assess it in a different way. (Dr. Rubino consults with manufacturers of obesity drugs and medical devices.)

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

“We have struggled with the inaccuracy of how we define what constitutes an inappropriate weight,” said Dr. Mariel Jessup, the association's chief scientific and medical officer. “How do you define ideal weight and disease weight?”

“We were asked many times, 'Do you think obesity is a chronic disease?' We were not happy to say 'yes' or 'no,'” she said. “We think it's more subtle.”

Rebecca Poole, associate director of the Rudd Center for Food Policy and Health at the University of Connecticut, believes the committee's approach “attempts to reduce some of the misconceptions about obesity that could potentially reduce stigma.” said.

“Obesity continues to be seen as a character flaw rather than a complex health condition,” she says.

However, it may be difficult for the new definition to enter general use.

Experts have long complained about the reliance on BMI to define overweight and obesity.

Measuring the index is easy. All you need is the person's height and weight. It quickly became the criterion for defining whether people are underweight, overweight, or obese.

And Dr. David M. Nathan, professor of medicine at Harvard Medical School and founder of the Diabetes Center at Massachusetts General Hospital, says BMI is well established as a major risk factor for diabetes, heart disease, cancer, and other conditions. said.

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

Dr Nathan said: “It's unrealistic to say the whole world will change like this.”

Equally unrealistic, he continued, obesity should not be treated until complications occur. “Obviously, you wouldn't treat high blood pressure until the person has had a stroke,” Dr. Nathan says.

While not all people who are obese will develop serious health problems, “the number of people who don't develop some kind of weight-related complication is quite small,” Dr. Nathan added.

Use of the new standards may also impact new obesity drugs and other drugs brought to market. They are so expensive that some health systems that originally covered them for people who are obese, as defined by BMI, have decided they can no longer afford to do so.

But committee member Dr. David Cummings, an obesity expert at the University of Washington, suggested it might be limited to patients diagnosed with clinical obesity.

That group's needs are “more compelling,” he says.