At the beginning of the study, all participants had tests of fat levels in the blood (HDL, LDL, total cholesterol, and triglycerides) and completed a survey about diet habits. They were randomly assigned to take either HRT pills (consisting of the hormone estrogen) or placebo pills for the next 9 months. Women with a uterus who were assigned to the HRT group were also given progesterone (another hormone) to avoid overgrowth of uterine tissue that could become cancerous, while those in the placebo group received placebo pills. Thirty-nine women received active HRT, and 20 women received placebo. Nine months after the study began, fat levels in the blood were tested again.