Relationship of Diet and Body Composition to Menstrual Irregularities in Female Runners

The relationship of nutritional intake and body composition to menstrual irregularities was studied in 40 female runners (24 eumenorrheic and 16 oligo/amenorrheic) between the ages of 18-35 years and running 20 or more miles per week. Subjects were recruited from college cross country teams that attended an NCAA Cross country championship, local track club, and University. Eumenorrhea was defined as having 9-12 periods per year while oligo/amenorrhea was defined as having 8 or less periods per year.

A semi-quantitative food frequency was used to evaluate dietary intake for calories, percent of calories from protein and fat. While skinfold measurements (thigh, suprailium, and tricep ), waist and hip circumferences, and height and weight were used to evaluate body composition and shape.

Both oligo/amenorrheic and eumenorrheic subjects showed no significant differences in age, menarche, years run, weekly miles run, and intensity. In addition, there was no significant difference in height (65.73 and 64.71, respectively); weight (115.61 and 116.79, respectively); waist:hip ratio (.73 and .72, respectively). Contrary to expectation, there was also no significant difference in nutritional intake (calories, calories per kilogram, calories per kilogram lean body mass, and calories per weekly miles run; percent of calories from fat, percent of calories from protein, and grams of protein per kilogram body weight). Percent body fat and body mass index (BMI) were the only significant differences between the two groups: both were significantly lower in oligo/amenorrheic runners (12.37% and 18.85, respectively) compared to eumenorrheic runners (14.19% and 19.63, respectively). No significant differences were found in nutritional intake.

These findings suggest that low body fat is a primary factor related to menstrual status. However, although statistically significant, both groups were of very low fat body composition and differing by only about 2%. The clinical significance of this difference should be investigated. The conflicting results of this study compared to past studies is an indication that the development of oligo/amenorrhea is complex and probably caused by more than one factor other than just body fat composition.