The Effects Of The Menstrual Cycle On Body Water Composition

It is common for females to experience feeling of bloating during the ovulation phase. This has been related to an increase in water retention as a result in increased levels of estrogen. As hormone levels fluctuate during the menstrual cycle one might expect changes in body water composition to change as well. PURPOSE: To determine if body water composition changes over the course of the female’s menstrual cycle. METHODS: Eight females (20.5 ± 0.5 year) who had regular menstrual cycle and were free of hormonal contraceptive visited the lab 7 times. The visits were in the following phases: menstruation (M): 24 and 96 hours after the first signs of menstruation, Follicular (F):24 and 72 hours after the end menstruation, Ovulation (O): within 24 hours of positive ovulation test, and Luteal (L): 5 and 10 days after ovulation. On each day the participants had their total body water (TBW), intracellular body water (ICW) and extra cellular water (ECW) measured via Bioelectrical Impedance Analysis. If there were two measurements for the phase the measurements were averaged and a repeated measures ANOVA was run to determine differences between phases. RESULTS: For TBW there was no significant difference between phases (F = 0.8, P = 0.4) with the values for each phase (mean ± SD), M: 31.1 ± 2.33, F:30.8 ± 2.1, O:31.25 ± 2.5, L:30.8 ± 2.3 kg. For ICW there was no significant difference between phases (F = 0.7, P = 0.6) with the values for each phase (mean ± SD), M: 16.9 ± 1.5, F:16.9 ± 1.1, O:17.26 ± 1.5, L:16.7 ± 1.3 kg. For ECW there was no significant difference between phases (F = 1.5, P = 0.2) with the values for each phase (mean ± SD), M: 13.9 ± 1.5, F:12.9 ± 2.7, O:13.9 ± 1.5, L:14.1 ± 1.5 kg. CONCLUSION: The results of this study did not indicate that there was a significant change in water composition in females during different phases of their menstrual cycle. Hormone based water retention has been speculated as the cause of bloating, however other mechanism may lead to feelings of bloating as may not be water retention but water redistribution.