Energy intakes are higher during the luteal phase of ovulatory menstrual cycles

We compared energy and macronutrient intakes across the menstrual cycle in participants (n = 42) in a study that assessed the frequency of ovulatory disturbances in regularly cycling vegetarians and nonvegetarians. Women kept daily basal body temperature records for six consecutive menstrual cycles and provided 3-d diet records near the beginning, middle, and end of different cycles. On completion of the study, temperature records were quantitatively analyzed to determine whether cycles were ovulatory, and if so, the date the luteal phase began. Diet records kept near the beginning and end of cycles were matched with temperature analysis results, and women were grouped according to whether the end-of-cycle record was kept during the luteal phase of an ovulatory cycle (group 1, n = 29), or during an anovulatory cycle or before luteal phase onset of a short luteal phase cycle (group 2, n = 13). Group 1 had higher energy intakes during the luteal than during the follicular phase (9.27 +/- 2.69 vs 8.01 +/- 2.36 MJ/d, P < 0.0001), whereas intakes of group 2 did not differ across the cycle (7.91 +/- 2.18 vs 8.20 +/- 1.48 MJ/d, NS). Both groups' macronutrient intakes were similar in records kept near the beginning and end of cycles. Documentation of ovulation is necessary in studies assessing premenopausal women's energy intakes.