Tamoxifen is the gold standard for endocrine treatment of estrogen-receptor positive breast cancer. Tamoxifen is also known to have metabolic effects. A new study reports that the drug also prevents obesity, fatty liver, and insulin resistance in female mice who were fed a high-fat diet and whose ovaries had been removed. The study was also able to pinpoint which estrogen receptors underlie these protective effects, opening up possibilities for new therapies to treat these conditions.