If you want to get people talking, just mention three little words — body mass index (BMI). BMI has been in the hot seat a lot over the years. Critics of it have said that it’s old-school, it doesn’t distinguish between excess fat, muscle or bone mass and it doesn’t give an accurate picture of our overall health. Recently, another issue was added to the pile — BMI could prevent people of color from having their risk for Type 2 diabetes assessed earlier.
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What the latest research shows
Recently, researchers in the U.K. discovered that the cutoff BMI number associated with a higher risk of Type 2 diabetes varies between different patient populations. For example, a BMI of 30 or above was linked to a higher risk for white people. For Black people, the cutoff number was 28 or above. For South Asian people it was 23.9 or above and for people of Arabic descent, the BMI cutoff was 26 or above.
The problem? Some healthcare providers might only be making recommendations for diabetes-related lifestyle changes or treatment options based on the risk level for white people. This means some people of color might not get the medical interventions they need in time.
Psychologist and weight management specialist Leslie Heinberg, PhD, MA, explains why BMI is still used and gives some tips for how people of color can make sure they’re on the right track despite the discrepancies.
Where did BMI come from?
The formula for calculating body mass was the creation of a Belgian mathematician, astronomer, sociologist and statistician named Lambert Adolphe Jacques Quetelet. Quetelet wasn’t focused on studying obesity when he developed what was first known as the “Quetelet Index” (your weight in kilograms divided by the square of your height (in meters) or Kg/M2). He was looking at years of crime data that he compiled to link crime to social conditions. In doing so, he noticed a relationship between an adult’s height and weight.
In 1972, American physiologist Ancel Keys gave the Quetelet Index a new name as he thought the formula was a good way to identify obesity. He referred to it as the body mass index.
“It’s a ratio that takes height into account because taller people weigh more than shorter people,” says Dr. Heinberg. “It was developed more for actuarial tables and to determine which people are at a higher risk for mortality. It’s something that makes sense when you look at a very large population. When you’re looking at millions of people, we know that a BMI over a certain amount is associated with more health problems or poorer longevity than in the normal range, and very low BMI is also associated with a whole host of problems. But overall, BMI was developed for large populations.”
Dr. Heinberg adds that today, many organizations and businesses still rely on BMI when it comes to providing things like insurance or medical procedures.
The drawbacks of BMI
Dr. Heinberg says that BMI can be a pretty blunt instrument for health because it leaves a lot of physical attributes out of the equation.
“It doesn’t take into account a lot of things about an individual. You can ask somebody for their height and weight and it becomes a very easy assessment in comparison to a full and comprehensive evaluation. When we think about an individual’s health and their health risks, taking their background information into account is helpful. But when you’re looking at a million people, you just can’t do that.”
Dr. Heinberg illustrates this by pointing out that a lot of professional athletes would be considered to have obesity based on BMI because they have more lean muscle mass as compared to people with similar BMIs who aren’t as active. In comparison, while they all might have the same BMI, they obviously won’t have the same health. So BMI is like one paint stroke in the overall picture of someone’s health.
And as the study suggests, Dr. Heinberg gives a few examples of how BMI could prevent people from getting the care they need.
“Insurance companies will pay for bariatric surgery if people have a BMI above 40 or if they have a BMI of 35 and at least two weight-related health problems like high blood pressure or Type 2 diabetes. That becomes problematic if someone falls below that range due to their ethnicity because they might have health problems and could benefit from metabolic surgery. That’s just one real-world example of how BMI might hurt people who do need care.”
On the other hand, Dr. Heinberg says that BMI can affect healthy people negatively as well.
“On the flip side, someone may be quite fit and metabolically healthy, but because of where this chart says they fall, they’re kind of pressured or pushed to lose weight by their healthcare provider. Unfortunately, that can be a stigmatizing experience. And even though that person is healthy and they’re fit, their BMI doesn’t quite fall under what is considered ‘normal.’”
Other physical signs of health risks
While BMI is one way of measuring risks, Dr. Heinberg says there are other physical clues to watch out for.
“We do know things like waist circumference, waist-to-hip ratio and where you hold excess weight might play an even more important role when it comes to metabolic diseases,” she says.
For instance, if you have an apple body shape or a pear shape, the excess abdominal weight of an apple shape is associated with more cardiovascular risks and metabolic disease. “Also, with things like obstructive sleep apnea, neck circumference seems to be important. It all goes way beyond just BMI.”
How people of color can advocate for their health
Since BMI originated with the measurements of European men, we know that it leaves a wide range of people out of the equation. However, since it’s just one piece of information, Dr. Heinberg recommends getting the full picture of your health.
“What’s helpful about this study is that it helps illustrate that BMI should not just be used to determine if someone is healthy, unhealthy, lean or has obesity. Instead, it should be considered as another vital sign. If a provider sees someone with an elevated BMI, particularly if they’re from a subpopulation that is at higher risk for Type 2 diabetes, that should suggest doing some lab work and making additional assessments. It would also be good to discuss any factors that can keep a person out of that range of prediabetes or diabetes.” These factors might include sleep habits, stress management, dietary changes and increased physical activity.
If you already know that your family has a history of diabetes, high blood pressure or other health concerns, discuss it with your provider. The more information they have, the better equipped they are to monitor your health and help you manage any conditions.
“If your physician is not assessing these things, it would absolutely be a good thing to say, ‘I know my family has a history of diabetes,’ or ‘I know that because of my ethnicity, I am at higher risk. Is this something that should be monitored?’”
The main thing to keep in mind about BMI
Dr. Heinberg says the other important message when it comes to BMI or weight is that you don’t have to lose a large amount of weight to improve your health.
“There’s this unfortunate message that everyone has to be within this little window. But even a small amount of weight loss — five to 10 pounds — is associated with really significant improvements in metabolic risk or cardiovascular risk. People don’t need to get to their high school weight. They don’t have to get into their skinny jeans. A small loss can mean really big gains in terms of health.”