Why BMI has been criticized for years as a failing indicator of health

He Body mass index (BMI) has appeared for decades as one of the measures of health most used .

This is, generally speaking, an indicator that takes into account weight and height of a person to determine if they can be classified as overweight, obese or extremely obese.

But although it has been widely used as a detection tool, Many doctors, nutritionists and researchers have criticized BMI for years. .

Largely because they consider it not really effective when it comes to assessing health risks, because does not distinguish between certain fundamental variables .

This is why many experts in related fields used other indicators to assess the situation of their patients.

An academic journal available on the website of the US National Institutes of Health (NIH, for its acronym in English) ensures that “BMI does not correctly assess body fat percentage and muscle mass, nor does it distinguish abdominal fat from gluteofemoral fat” .

“It is important to keep this in mind because Abdominal fat is associated with insulin resistance, metabolic disease and cardiovascular complications “.

The authors of the research, originally published in The Cureus Journal of Medical Sciences in 2023, they claim that Its use by professionals, without considering other variables, can affect treatment, prevention and patient outcomes. general health.

“There are several different anthropometric indices which more precisely assess abdominal adiposity by integrating waist circumference and have been widely studied, such as the waist-hip ratio, the waist-height ratio and a body shape index”, they anticipate in their writings.

Likewise, they emphasize that it is extremely important “that Consider replacing the use of BMI in healthcare with a different anthropometric index. “.

“One that accounts for differences in height, gender, and race, takes into account abdominal adiposity, and more accurately predicts the relationship. between obesity, mortality and diseases such as cardiovascular disease, hypertension, insulin resistance and diabetes.

In 2023, the American Medical Association (AMA), shared a statement in which it describes BMI as “an imperfect way to measure body fat in multiple groups” .

This is due, the organization explains, to factors such as “does not take into account differences between racial/ethnic groups, sexes, genders and age groups” .

“Due to the significant limitations associated with the widespread use of BMI in clinical settings, The AMA suggests that it be used in conjunction with other valid risk measures. such as, among others, measurements of visceral fat, body adiposity index, body composition, relative body fat, waist circumference and genetic/metabolic factors,” we read further in the same document.

According to former AMA President Jack Resneck Jr., “There are many concerns about how BMI has been used to measure body fat and diagnose obesity, but some doctors consider it a useful measure in certain situations “.

He nevertheless stressed that “it is important for doctors to understand the benefits and limitations of using BMI in the clinical setting, to determine best care for their patients. »

Director of the Metabolic Health and Weight Loss Program at Yale University, Wajahat Mehal, told the New York Times that This indicator does not distinguish between those who have a lot of muscle mass and those who have fat in different parts of the body. .

As an example, he said: “According to BMI, Arnold Schwarzenegger, when he was a bodybuilder, would have been considered obese and would have needed to lose weight” .

“But as soon as you measured it size, you’d see, ‘Oh, that’s 32 inches “, he added.

The researcher from the Center for Evidence-Based Medicine at the Capital Institute of Pediatrics in Beijing (China), Wenquan Niu, reiterated to the American newspaper that this indicator “does not distinguish between body fat and muscle mass”, so “for any BMI, fat distribution and body composition can vary considerably” .

According to the expert, “when the BMI is used to control risk, often overestimates the risk for muscular athletes, while underestimating the risk for older people whose muscle mass has been replaced by fat “.

Fat stored in the abdominal cavity is important because it surrounds organs such as the heart and liver. while it is associated with diagnoses such as insulin resistance and glucose intolerance, which tend to precede type 2 diabetes.

In the same way, promotes high blood pressure and lipid abnormalities this can lead to heart disease.

Niu emphasized that “Excessive visceral fat deposition is like a silent killer that hides in our body and can attack a person for years with few visible symptoms, especially in apparently thin people.

Specialists have proposed another measurement known as the body curvature index (CRI), which measures the circumference of a person’s body based on a formula that takes into account their height and waist circumference .

SO, don’t focus on weight .

Research published in June 2024 in Open JAMA Network declares that The CRI takes into account factors such as central obesity and abdominal fat which are linked to an increased risk of type 2 diabetes, hypertension and heart disease.

Wenquan Niu and his colleagues developed A digital calculator this allows us to know this indicator .

On this, he said that scores are usually between 1 and 15, while most people are between 1 and 10 years old .

A study reviewed by The Times analyzed a sample of 33,000 Americans and identified that CRI scores increased between 1999 and 2018 .

While The higher the score, the more circular it is or “round” is the body.

They found that those who had 6.9 years or older were at higher risk of dying from cancer, heart disease or other illnesses. evils.

In this sense, their risk of mortality was almost 50% higher than those with a CRI of 4.5 to 5.5, i.e. the average of the sample.

Along with this, those who had a score 5.46 to 6.9 faced 25% higher risk compared to those in the mid-range.

On the other hand, Those with a CRI below 3.41 had a 25% higher mortality risk than those in the mid-range.

The latter is due, as the authors of the work suggest, to the fact that lower scores could reflect nutrition problems, inactivity, or muscle atrophy .

It is worth remembering that if you have doubts about your health, it is always advisable Visit a specialist to assess your case and the best ways to approach it .