Culture and menstruation the ideal of synchronised tidal, lunar, menstrual and seasonal periodicities whose overall harmony (it is believed) confers spiritual power and fertility. To many, such cultural associations appear persuasive in view of the fact that in humans, the menstrual cycle quite closely approximates the moon's 29.5-day synodic cycle, unlike in chimpanzees (~36 days) or bonobos (~40 days). Statistical information from hunter gatherers is lacking, but where large-scale western studies focus on women's peak reproductive years—removing outlier values—the cycle length gravitates around 29.1–29.5 days, while the figure for women in their thirties shortens toward 28 days. In no extant human population has
Menstrual cycle enhanced during the luteal phases of the menstrual cycle. This is due to the higher metabolic demand during this phase. In particular, women tend to show a cravings for chocolate, with higher cravings during the luteal phase. Females with premenstrual syndrome (PMS) report changes in appetite across the menstrual cycle more than non-sufferers of PMS, possibly due to their oversensitivity to changes in hormone levels. In women with PMS, food intake is higher in the luteal phase than follicular. The remaining symptoms of PMS, including mood changes and physical symptoms, also occur during the luteal phase. No difference for preference