Menstrual synchrony
Strassmann argued menstrual synchrony defined as menstruation overlap should be quite common. For example, the expected difference by chance between two women with 28-day cycles—which is approximately the average length of menstrual cycles of women at the age —is 7 days. Considering that the mean duration of menses is 5 days and the range is 2 to 7 days, the probability of menstruation overlap by chance should be high.
Menstrual cycle
Females have been found to experience different eating habits at different stages of their menstrual cycle, with food intake being higher during the luteal phase than the follicular phase. Food intake increases by approximately 10% during the luteal phase compared to the follicular phase.