Changes in body weight and body composition during the menstrual cycle

Objectives: The general perception is that menstrual cycle is a factor related to body weight and body composition fluctuations in women. The lack of a standardized methodology of the so far conducted studies has led to controversial results. The aim of the current study is to identify if there are any changes in body weight and body composition during the menstrual cycle. Methods: In the current study measurements of body weight, circumferences, skinfolds and body composition with bioelectrical impedance analysis were conducted twice per week in 42 women during their menstrual cycle. Results: Body weight was found to be statistically significantly higher during menstruation compared to the first week of the menstrual cycle by 0.450 kg, which could be attributed to a statistically significant increase of 0.474 kg observed in extracellular water. No other statistically significant changes were observed regarding body composition. Conclusions: An increase of approximately 0.5 kg was observed during women's menstrual cycle, mostly due to extracellular fluid retention at menstruation days. These findings could be taken into account to interpret body weight and composition periodic fluctuations in women of reproductive age.