Researchers at the Institute for Systems Biology have developed a biological BMI as a more accurate indicator of metabolic health instead of the traditional BMI based on height and weight[1]. The study included 1,000 participants in a wellness program who analyzed more than 1,100 substances in their blood, such as proteins and metabolites, along with genetic risk scores and gut microbiome composition at different time points[1]. Using machine learning, they created models that predict metabolic health more accurately than traditional BMI[1]. The main findings show that people with a high biological BMI but a normal traditional BMI are less healthy but lose weight more easily after lifestyle changes[1]. On the contrary, those with obesity according to the traditional BMI, but a normal biological BMI, are biologically healthier and it is more difficult for them to lose weight[1]. With positive lifestyle changes, the biological BMI decreases faster than the traditional one, indicating an improvement in health even without visible weight loss[1]. This multi-omic analysis highlights the interactions of adipose tissue, microbiome and metabolism in defining metabolic obesity[1].