This is an observational study to investigate the effect of endogenous estrogen (E2) and progesterone (P4) levels on eating behavior and energy-yielding nutrient metabolism. Eating behavior will be assessed during a complete menstrual cycle during the first month of the study. Participants will track the follicular and luteal phases of their menstrual cycle using urinary leuteinizing hormone (LH) kits, they will record information about their food intake, eating behaviors, and appetite in their home environments, and they will complete two laboratory test days: one test day scheduled during their follicular phase, and one test day scheduled during their luteal phase.
