For decades, health professionals have relied on body mass index (BMI) to assess a person’s weight and classify them accordingly. It is calculated by dividing a person’s weight in kilogrammes by height in metres squared. In other words, BMI = kg/m².
The result is used to classify individuals into several categories, ranging from underweight to morbidly obese. This index has become a standard and is used to evaluate potential health risks related to a person’s weight, such as diabetes or cardiovascular disease.
But BMI may be too simplistic, according to researchers at the Institute for Systems Biology in Seattle, Washington. According to them, 30% of the American population could be misclassified by this approach.
This is why they propose a new BMI, the so-called “biological BMI”, taking into account more varied measurements and promising to provide a more precise representation of a person’s health.
To conduct their research, published in the journal “Nature Medicine”, they focused on 1,000 adults enrolled in wellness programmes. They studied more than 1,100 blood analytes, such as proteins and metabolites, as well as genetic risk scores and the composition of gut microbiota collected at different times.
Then, using machine-learning models, the researchers generated more accurate predictive variations of a biological BMI than traditional measures of BMI alone.
“We now have the capability to use advanced molecular measurements as a more comprehensive representation of a person’s metabolic health, which can be used to make more accurate clinical recommendations for individuals,” said Noa Rappaport, senior research scientist and corresponding author of the paper.
The team found several important things. First, people with a high biological BMI but a normal traditional BMI were found to be less healthy. Nevertheless, they were able to lose weight more easily when making changes to their diet and lifestyle.
On the other hand, people classed as obese with a traditional BMI but with a normal biological BMI were found to be more healthy. However, they had greater difficulty losing weight.
Another finding notes that when participants made the right lifestyle changes, their biological BMI decreased more rapidly than their traditional BMI.
“This work is a valuable asset for comprehending the molecular changes associated with obesity and metabolic health,” said Kengo Watanabe, lead author of the study.
“And it has the potential to significantly improve the development of predictive and preventive clinical approaches for treating metabolic disturbances.”