BMI is an ‘imperfect’ way of measuring health. But replacing it is complicated

Vishal Gentle isn’t the avid gym goer he was before his daughter was born a few months ago.

But the new dad said he’s doing what he can to stay active — carrying baby up and down stairs for a little exercise, walking a lot and using a standing desk.

Gentle said he feels healthy, but according to body mass index, or BMI, he is overweight.

“Honestly, I’m not overweight. I mean, except a little bit around my waist. But like I’m fully active. I can do anything and everything,” he said during an interview at his Toronto home.

Gentle is not alone when it comes to whether his BMI is an accurate measure of health. BMI is increasingly under scrutiny – both for its usefulness as a measure of health and for its problematic origins.

BMI is calculated by dividing weight in kilograms by height in meters squared. The result can be compared to the BMI chart, easily found on the internet, social media and in doctor’s offices, which advises the user directly whether the result is underweight, normal, overweight or obese.

Last month, the American Medical Association (AMA) formally recognized the shortcomings of BMI and created a new policy that advises caution in its use.

In a June press release, the AMA warned that BMI is an “imperfect way to measure body fat in multiple groups, as it does not account for differences between race/ethnic groups, sexes, sexes, and ages.”

It also notes that BMI, which dates back to the 19th century, has a problematic basis.

“Under the newly adopted policy, the AMA acknowledges problems with using BMI as a measure because of its historical harm, its use for racial exclusion, and because BMI is primarily based on data collected from previous generations of non-Hispanic white populations,” the press release states.

The AMA encouraged clinicians to use other factors such as waist circumference, fat distribution and genetic factors when assessing a patient’s health.

Growing criticism

The AMA’s position is the latest mounting criticism of the BMI.

The inability to differentiate between mass created by fat, muscle and bone has been identified as a shortcoming by experts and health authorities, as has the lack of distinction for where fat is distributed across the body.

They note that belly fat may be a risk factor for conditions such as diabetes and heart disease, while hip and thigh fat is less associated with health problems.

Dr. Sanjeev Sockalingam, Obesity Canada’s Toronto-based scientific director, said he hopes the AMA’s position will accelerate work to find better ways to assess health, and in particular to evaluate obesity as a medical condition .

“I hope that this will actually generate some more research in this area, which I think is much needed given all the challenges and issues we’ve identified with BMI,” he said.

Obesity Canada’s latest practice guidelines leave BMI out of the definition of obesity and instead describe it as a chronic medical condition leading to disability and disability.

Why does the BMI stick?

Still, BMI calculators are easy to find on organization websites such as the Canadian Cancer Society And diabetic Canada.

Health Canada promotes the use of BMI and has the chart on its website, but notes that the measure should not be used by people under the age of 18, or by people who are pregnant or breastfeeding.

The agency has recommended using BMI in conjunction with waist circumference measurement since 2003, spokesman Nicholas Janveau said in an email.

“Although BMI has some limitations, it is still the preferred measure of excess body fat for population-level surveillance and epidemiological studies because of its simplicity and ease of estimation,” Janveau said.

Despite all of Sockalingam’s misgivings about BMI, he said it cannot be abandoned just yet because it is deeply integrated into clinical trials and other aspects of healthcare.

“We don’t want to remove it at this point without something replacing it, because it’s been so hard to get people to recognize obesity as a chronic medical condition and to think about patient-centered approaches and treatments that are now emerging. are for people living with obesity,” he said.

He advises people to think of BMI as a high-level screening tool, but not rely on it for diagnosing an individual.

What is the alternative?

Dr. Sonia Anand, a vascular medicine specialist at McMaster University in Hamilton, Ontario, said she agrees it would be difficult to disassociate BMI from its place in clinical settings, research and the weight loss industry.

She knows it’s not going away any time soon, but said she’d like to see it replaced with waist circumference as a free, easy measurement.

“It’s deeply ingrained in our way of thinking. But now is reasonable, a good time for different healthcare providers, agencies, trialists and individuals to measure waist circumference and use that along with body weight,” Anand said.

Anand has researched how South Asian people experience metabolic changes, such as increases in blood sugar, blood pressure and cholesterol, at a lower cut-off point than white Europeans.

She said continuing to rely on BMI for people of different backgrounds and lifestyles means you run the risk of missing signs to test for metabolic changes, or someone with a lot of muscle mass and a high BMI being wrongly advised to lose weight .

By itself, waist circumference is also not the gold standard in assessing health, Anand said, but she added that it can better assess whether someone has excess body fat in a specific area that can increase the risk of health problems.

A holistic approach

When it comes to diagnosing and treating obesity, Sockalingam said he would like to see a more holistic assessment.

“Ultimately, we want to look at how obesity affects an individual in terms of their daily life, their functioning and their co-occurring conditions, whether physical or mental health,” he said.

Anand and Sockalingam agree that even if dissatisfaction with BMI rises as the measure of health increases, it will be some time before widespread change occurs. Sockalingam said he hopes people who hear about the problems with BMI will be empowered to ask their health care providers for different types of assessments.

Vishal Gentle said he had those conversations with his GP in Toronto, who told him he is not overweight.

He said it is important for him to keep a close eye on his health because his father died at the age of 67 during cardiac arrest.

Gentle said his father carried weight on his stomach, so his doctor’s advice to focus on eating right, exercising, and keeping an eye on waist circumference makes sense to him.

“As long as I can feel good and go about my daily activities, I have no problems,” he said.