Some diseases may occur with 'normal weight'

Body mass index (BMI) has long been considered a fundamental tool for assessing obesity and its associated health risks. However, recent research suggests that this traditional metric may conceal serious metabolic disorders that do not necessarily manifest in apparent weight.

A new study led by researchers from the University of Gothenburg in Sweden has identified a more accurate measure known as the Metabolic Body Mass Index (MetBMI). This metric relies on internal biological indicators that reflect metabolic efficiency, rather than relying solely on height and weight.

According to the study, an elevated MetBMI is associated with a significant increase in the risk of developing type 2 diabetes, as well as cardiovascular and metabolic disorders.

Researchers note that while the traditional BMI is easy to calculate, it overlooks essential factors such as where fat is stored in the body, how adipose tissue processes energy, and the body’s efficiency in converting food into fuel.

Dr. Rima Chakaroun, a professor of endocrinology at the University of Gothenburg, stated that “MetBMI reveals hidden metabolic disturbances that do not always show up on the scale.” She explained that variations in metabolic function and adipose tissue can make a person with a normal weight more susceptible to disease than someone who is overweight.

The study, published in the journal Nature Medicine, analyzed health data and blood samples from 1,408 individuals to develop an algorithm that measures MetBMI based on metabolic byproducts in the blood, many of which are produced by gut bacteria during digestion.

The model was then tested on an independent group of 466 people, demonstrating a higher ability than traditional BMI to predict diabetes, fatty liver disease, and metabolic syndrome.

The results showed that individuals whose MetBMI was higher than expected relative to their weight were 2.6 times more likely to develop type 2 diabetes and up to five times more likely to develop metabolic syndrome.

The study also revealed a strong link between MetBMI and gut bacterial diversity. High MetBMI scores were associated with reduced microbiome diversity and a lower presence of bacteria capable of breaking down dietary fiber. Researcher Fredrik Backhed emphasized that this opens the door to dietary and lifestyle interventions that could improve metabolic health even without significant weight loss.

The researchers concluded that while the new index requires further validation before clinical adoption, it may contribute to more accurate health risk assessments in the future, particularly for individuals who appear to have a normal weight but are at high risk internally.