Estrogens have profound effects on metabolism and weight gain in women and female rodents. For example, post-menopausal women have decreased levels of estrogens and tend to gain weight, which increases their risk of obesity, diabetes, heart disease and cancer. The gut microbiome, the collection of bacteria and viruses in the gut and the chemicals they produce, is important in maintaining a healthy gut and immune system. In addition, the gut microbiome has been implicated in a variety of disorders and diseases, including diabetes and obesity.  In this presentation, I will discuss our collaboration with Dr. Jason Kim (UMass Medical School) to study the effects of estrogens and diet on metabolism and gut microbiota in female mice.