You weigh just right, exercise and feel healthy. Nevertheless, your metabolism may already be derailed. One in three people of normal weight has dangerous changes in their body that are not recorded by the classic BMI. Researchers at Leipzig University, together with colleagues from Gothenburg, have now developed a new index. It shows the true risk of disease.
The body mass index is calculated from height and weight. It shows whether someone is overweight. But it reveals nothing about how healthy the metabolism is. Some people are slim, but their bodies process sugar and fats poorly. Others weigh more, but their metabolism still runs smoothly. The scientists wanted to close this gap.
"Our metabolic BMI reveals a hidden metabolic disorder that is not always visible on the scales," says Dr. Rima Chakaroun from Leipzig University Medicine. She led the study during a guest stay at the University of Gothenburg. Two people could have the same BMI but have completely different risk profiles depending on the function of their metabolism.
Blood analysis instead of scales
For their study, the international team analyzed data from almost 2,000 people. They measured hundreds of small molecules in the blood. These metabolic products show how the cells work. With the help of artificial intelligence, the researchers developed a calculation model. It predicts the metabolic BMI - a value that reflects the metabolism.
The result is alarming. People with a normal weight but a high metabolic BMI have up to five times the risk of disease. These include fatty liver, diabetes and insulin resistance. With the latter, the body's cells no longer react properly to the blood sugar-regulating hormone insulin. These patients also accumulate more fat around their internal organs. In addition, they lost 30 percent less weight than expected after gastric surgery at Leipzig University Hospital.
Intestinal bacteria as the key
The researchers also discovered a close connection with the intestinal bacteria. People with a poor metabolic profile had fewer different types of bacteria in their gut. Their intestinal flora was less able to convert dietary fiber into healthy fatty acids. An important one of these is butyric acid, which inhibits inflammation.
The good news: genes play a smaller role in metabolic BMI than lifestyle and environment. This means that people can take countermeasures through their behavior. "The traditional BMI often overlooks people who are of normal weight but have a high metabolic risk," explains Chakaroun. The new index could contribute to a fairer assessment of disease risk.
The researchers have already simplified their model. Instead of over 1,000 metabolic products, 66 values are now sufficient for a reliable statement. This makes the test easier. In future, the scientists want to further improve the model. Dr. Chakaroun will continue her research at the Cluster of Excellence Leipzig Center of Metabolism.
