In a study that was published in Cell Metabolism, researchers prove, through clinical trials, that the mathematical modelling they developed works.In the study, the gut microbiome was characterised for individuals in a group of overweight patients, and then they were put on a weight loss diet. Everyone lost weight, which was expected. In patients with low-diversity gut microbiome, however, the content of several substances that generally indicate health risks was also reduced in the individuals' blood and faeces.