Moderate exercise has many benefits to the overall health of premenopausal women, but intensive or excessive exercise can contribute to amenorrhea and increase the risk of early bone loss due to detrimental effects on hormone balance.8 Exercise typically increases bone density, but a study of dancers with amenorrhea found that bone density measurements remained below normal for the entire two-year duration of the study.9 The demands placed upon women performers and athletes are believed to contribute to the high incidence of eating disorders among them. This, along with the increased physical and nutritional demands of intensive exercise, can lead to nutrient deficiencies and lowered body-fat percentages that may contribute to amenorrhea and bone loss in women athletes.10, 11, 12 Running and ballet dancing are among the activities most closely associated with amenorrhea,13 with as many as 66% of women long-distance runners and ballet dancers experiencing amenorrhea.14 Among women bodybuilders in one study, 81% experienced amenorrhea, and many had nutritionally deficient diets.15 While some amenorrheic athletes have been reported to resume menstruation after adding one day of rest per week and consuming a daily nutritional beverage containing additional calories, protein, carbohydrate, fat, vitamins, and minerals,16, 17 no controlled trials have investigated this approach.
Hormonal changes associated with breast-feeding prevent menstruation in healthy women.18 The duration of this interruption in menstruation, known as lactational or postpartum amenorrhea, depends on many factors, including the nutritional health of the mother. Poor maternal nutritional status has been associated with longer periods of lactational amenorrhea in developing countries19, 20, 21, 22 as well as in Great Britain among poor nursing women.23 Better maternal nutritional status was found to be associated with shorter lactational amenorrhea in well-nourished nursing mothers in the United States.24 When malnourished nursing mothers are given food supplements, the length of lactational amenorrhea can be shortened, according to preliminary studies.25 However, one controlled trial found dietary supplementation with skim milk did not shorten the duration of amenorrhea in well-nourished nursing mothers.26 Although prolonged lactational amenorrhea prevents another pregnancy, it has not been shown to result in permanent bone loss.27
Excessive stress causes the body to produce increased amounts of the adrenal hormone cortisol, and several studies have linked high cortisol levels to low levels of reproductive hormones and to amenorrhea.28, 29, 30 In one study, amenorrheic women showed a greater increase in cortisol in response to stress than did women with normal menstrual cycles.31 No research has been done to evaluate stress reduction interventions for the treatment of amenorrhea.
Smoking may contribute to amenorrhea. A survey study found that young women smoking one pack or more per day were more likely to be amenorrheic than other women.32 However, whether smoking cessation will normalize menstrual function in amenorrheic women is unknown.