Imagine this: you’ve got an entire civilization of microbes living, somewhat happily, inside of you, and they make many of the decisions about your health. Now comes a group of researchers from the National Institute for Agricultural Research in France, who analyzed the microbes in the guts of 292 Danish people. As NPR reports, the researchers found that lean people had far greater (40 percent) microbial diversity than obese people. Wait, it gets worse: People who had less microbial diversity — whatever their weight — were more likely to have a variety of risk factors for Type 2 diabetes, heart disease and cancer. Those risk factors included insulin resistance and inflammation. What can you do about it? The researchers don’t have recipe for greater microbial diversity, but they do think a better diet–fewer calories, more grains– and also fewer antibiotics will help. Read more from National Public Radio.