Liping Zhao and colleagues, in their recent paper on a dietary intervention for simple and genetic obesity, discussed evidence for the existence of gut microbiota 'guilds': bacterial genomes within the gut ecosystem that responded to the dietary intervention as a group.

Obesity and type 2 diabetes mellitus (T2DM) are complex chronic diseases with rapidly growing prevalence across the world. Human studies have found that both genetic and environmental factors contribute to T2DM; the clearest lifestyle factors are high caloric intake and low physical activity. The mechanisms by which human T2DM arises is still unclear, but obesity, insulin resistance and ß-cell dysfunction all play a role.