Body mass index: an inaccurate measure of weight that affects treatment

People seeking treatment for weight problems or eating disorders expect their insurance to pay at least some of the cost. But whether it’s covered depends on a measure invented nearly 200 years ago by a Belgian mathematician who used statistics to find the “average person.”

In the 1830s, work by Lambert Adolphe Jacques Quetelet served life insurers, who developed “ideal” weight tables. In the 1970s and 1980s, the measure, now called body mass index (BMI), was adopted to detect and monitor obesity.

It is now common to use this mathematical equation – essentially a relationship between weight and height – to label patients as overweight, underweight or “healthy weight”.

It’s simple, there’s a scale that identifies adults who score between 18.5 and 24.9 as a healthy weight.

But critics say it was never intended as a health diagnostic tool. “BMI doesn’t come from science or medicine,” says Dr. Fatima Stanford, an obesity medicine expert and director of equity in the division of endocrinology at Massachusetts General Hospital.

Stanford and other experts say BMI can be good for tracking population weight trends, but it falls short because it doesn’t take into account differences between ethnic groups and because it doesn’t signal that some people, including athletes, are overweight or obese. Difference between muscle mass and fat.

Still, BMI has become a key standard used to determine who is most at risk for weight-related health outcomes and who qualifies for often expensive treatment.

Although there is much debate about BMI, there is a consensus in the medical field that people who are overweight or obese are at higher risk for several health problems including diabetes, liver problems, osteoarthritis, high blood pressure, sleep apnea. Cardiovascular conditions.

BMI measurements are usually included in indications when prescribing medications for weight loss. Some newer, more effective drugs, such as Wegovi, limit their use to those with a BMI equal to or greater than 30, the threshold for being considered obese, or below 27, but only if the patient has at least one weight-related condition. Medical problems, such as diabetes.

Doctors can prescribe the drug to patients who don’t meet these requirements, but insurers may not cover the cost.

Although most insurers, including Medicare, cover some form of bariatric weight loss surgery, they require the patient to have a BMI of at least 35 along with other health problems such as high blood pressure or diabetes to perform the procedure.

The situation can be more complicated when it comes to drugs. Medicare, for example, does not cover most weight loss medications, although it does cover behavioral health treatments and obesity screenings.

Private insurers vary in their coverage of weight loss drugs, so it largely depends on the patient’s specific policy.

“It’s very frustrating because everything we do in obesity medicine is based on these limits,” Stanford said.

Critics say BMI can err on both ends of the scale, mislabeling some large people as unhealthy, and others who are underweight as healthy, even though they may need treatment.

For eating disorders, insurers often use BMI and can limit treatment to only those who are underweight, excluding many who need help, explained Serena Nangia, director of communications for Project Cure, a nonprofit organization that helps patients get treatment.

“By focusing so much on BMI numbers, we’re missing people who could have gotten help earlier, even if they had a moderate BMI,” Nangia said. “If they’re not underweight, they’re not taken seriously and their behavior is ignored.”

Stanford said he has to confront insurance companies about their definition of who qualifies for BMI-based overweight treatment, especially when it comes to some new weight-loss drugs, which can cost more than $1,500 a month.

“I’ve had patients do well on medication and their BMI drops below a certain level, and then the insurer wants to stop their medication,” Stanford explained.

While it can be useful as a screening tool, Stanford and other experts say BMI alone is not a good arbiter of health.

“A person with a BMI of 29 may be in worse health than someone with a BMI of 50 if that person has high cholesterol, diabetes or sleep apnea,” Stanford said. Who is sick with high blood? I would say the most metabolically ill person.”

Experts say BMI may overestimate obesity in tall people and underestimate it in shorter people. There are also gender and ethnic differences that it does not take into account.

An example: “African American women with BMIs between 31 and 33 tend to have better health than those above 30,” Stanford says.

Meanwhile, some studies, such as the Nurses’ Health Study, have shown that Asians have a higher risk of developing diabetes than non-Hispanic whites and other ethnic groups. For this reason, some countries, such as China and Japan, have set lower BMI thresholds for overweight and obesity among people of Asian descent.

Although BMI is useful for researchers studying population weight, experts say it should not be the only measure used to assess patients’ health and weight.

“It has its limitations,” says David Creel, MD, a psychologist and dietitian at the Cleveland Clinic’s Bariatric and Metabolic Institute.

“It doesn’t tell us anything about the difference between muscle weight and fat weight,” he added, noting that “many athletes can be in the overweight category, or even reach obesity weight despite having muscle.”

Both the physician and the patient should take other factors into consideration. One is being aware of where the weight is distributed among them. Studies have shown that being overweight in the midsection increases the health risk of a person.

“If someone has thick legs and most of their weight is in their lower body, it’s not as damaging around their midsection, especially in the groin area,” Creel said.

Stanford agrees, noting that median weight is “a much better indicator of health than BMI,” since the likelihood of developing diseases like fatty liver or diabetes “is directly related to your body size.” Waist”.

Patients and their doctors can use a simple tool to assess this risk: the tape measure. Researchers say that, measured just above the hips, women should be 35 inches or less; Male, 40 inches or less.

There are other initiatives to define new ways to diagnose obesity, including a panel of international experts convened by the Lancet Commission, said Stanford, who is a member of the group. The approved new criteria will not only inform doctors and patients, but also affect insurance coverage and public health interventions.

Stanford itself studied a way to adjust BMI to reflect gender and racial differences. This includes, in part, several groups of risk factors for conditions such as diabetes, high blood pressure and high cholesterol.

According to that study, BMI cutoffs may be lower for Hispanic and non-Hispanic white men and women. For African-American women, the cutoff will be slightly higher.

“We don’t plan to eliminate BMI, but we do plan to develop other techniques to assess weight-related health,” Stanford concluded.

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