Body weight and food intake of women are analyzed over the whole menstrual cycle. Over 68—94
days body weight and food intake of eight women and three men are recorded. For food intake, a diary selfreport
method is used. The beginning of each woman's menstrual cycle is also recorded. Body weight and food
intake are regarded as stochastic processes. The theory of time series and spectral analysis is applied. As opposed
to the males, in the spectra of seven females, there is a peak at a frequency with the period of the respective
females' menstrual cycles. There are no further consistent differences. This sine wave reaches its maximum two
to three days before menses. The data suggest that, as a first approximation, the body weight of women during
a complete menstrual cycle can be described by a simple sine wave. For food intake, the spectra show hardly
any differences between females and males. However, it is shown that the same sine wave as in body weight
is also contained in the food intake of seven females, reaching its maximum about four days before menses.