Disordered Eating, Menstrual Irregularity, and Bone Mineral Density in Female Runners

COBB, KRISTIN L.1; BACHRACH, LAURA K.2; GREENDALE, GAIL3; MARCUS, ROBERT4; NEER, ROBERT M.5; NIEVES, JERI6; FRAN SOWERS, MARY7; BROWN, BYRON W. JR.1; GOPALAKRISHNAN, GEETHA1; LUETTERS, CRYSTAL1; TANNER, HEATHER K.1; WARD, BRIDGET1; KELSEY, JENNIFER L.1

Medicine & Science in Sports & Exercise:
CLINICAL SCIENCES: Clinical Investigations
Abstract

COBB, K. L., L. K. BACHRACH, G. GREENDALE, R. MARCUS, R. M. NEER, J. NIEVES, M. F. SOWERS, B. W. BROWN, JR., G. GOPALAKRISHNAN, C. LUETTERS, H. K. TANNER, B. WARD, and J. L. KELSEY. Disordered Eating, Menstrual Irregularity, and Bone Mineral Density in Female Runners. Med. Sci. Sports Exerc., Vol. 35, No. 5, pp. 711–719, 2003.

Purpose: To examine the relationships between disordered eating, menstrual irregularity, and low bone mineral density (BMD) in young female runners.

Methods: Subjects were 91 competitive female distance runners aged 18–26 yr. Disordered eating was measured by the Eating Disorder Inventory (EDI). Menstrual irregularity was defined as oligo/amenorrhea (0–9 menses per year). BMD was measured by dual x-ray absorptiometry.

Results: An elevated score on the EDI (highest quartile) was associated with oligo/amenorrhea, after adjusting for percent body fat, age, miles run per week, age at menarche, and dietary fat, (OR [95% CI]: 4.6 [1.1–18.6]). Oligo/amenorrheic runners had lower BMD than eumenorrheic runners at the spine (−5%), hip (−6%), and whole body (−3%), even after accounting for weight, percent body fat, EDI score, and age at menarche. Eumenorrheic runners with elevated EDI scores had lower BMD than eumenorrheic runners with normal EDI scores at the spine (−11%), with trends at the hip (−5%), and whole body (−5%), after adjusting for differences in weight and percent body fat. Runners with both an elevated EDI score and oligo/amenorrhea had no further reduction in BMD than runners with only one of these risk factors.

Conclusion: In young competitive female distance runners, (i) disordered eating is strongly related to menstrual irregularity, (ii) menstrual irregularity is associated with low BMD, and (iii) disordered eating is associated with low BMD in the absence of menstrual irregularity.

The “female athlete triad” (33) is the combination of disordered eating, menstrual irregularity, and osteoporosis/osteopenia seen in young female athletes. Disordered eating, which affects as many as two thirds of young female athletes (33), consists of restrictive eating behaviors that do not necessarily reach the level of a clinical eating disorder (2). Women athletes with disordered eating may limit their caloric and/or fat intakes but maintain high training levels, often resulting in a state of chronic energy deficit. Among other adverse consequences, energy imbalance has been linked to depressed estrogen levels, metabolic disturbances, and amenorrhea or oligomenorrhea (2,7,26,34,49,50). Amenorrheic/oligomenorrheic athletes on average have lower bone mineral density (BMD) than eumenorrheic controls (6,7,9,20,22–24,26,28,29,32,34,37–39,46,48,49). This bone deficit may be related to an increased incidence of stress fractures (1,10,30) and may be only partially reversible (16,18,21) putting women at risk for life-long health consequences.

The existence of the female athlete triad is implicit in studies that established a relationship between eating behaviors and menstrual irregularity (2,7,26,34,39,49,50) and those that established a relationship between menstrual irregularity and low BMD (6,7,9,20,22–24,26,28,29,32,34,37–39,45,47,48). However, few studies have actually measured menstruation, diet, and BMD simultaneously (7,23,26,34,39), and these studies were conducted, largely, before the female athlete triad was recognized as a distinct syndrome. Therefore, the female athlete triad has yet to be explored as a triad, and the complex relationships among all three components have yet to be established.

In this article, we examine eating attitudes and patterns, menstrual status, and BMD in a group of 91 competitive female distance runners, using data collected at the baseline examination of a randomized controlled trial. We examine the etiology of menstrual irregularity in this population, specifically as it relates to diet and eating behaviors. We address the question of whether low body weight can explain the differences in BMD between eumenorrheic and oligo/amenorrheic athletes, as several researchers have suggested (6,32,45,48) or if menstrual irregularity is associated with BMD independently of low weight. Finally, we examine the relationship between disordered eating and BMD independent from menstrual irregularity, a link that has not been well studied in female athletes.

Author Information

1Division of Epidemiology, Department of Health Research and Policy,

2Department of Pediatrics, Stanford University School of Medicine, Stanford, CA;

3UCLA School of Medicine, Los Angeles, CA;

4Veterans Affairs Medical Center and Stanford Medical School, Palo Alto, CA;

5Massachusetts General Hospital and Harvard Medical School, Boston, MA;

6Clinical Research Center, Helen Hayes Hospital and Columbia University, New York, NY; and

7Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI

Address for correspondence: Kristin L. Cobb, Division of Epidemiology, HRP Redwood Building, Stanford University, Stanford, CA 94305; E-mail: kcobb@stanford.edu.

Submitted for publication April 2002.

Accepted for publication November 2002.

©2003The American College of Sports Medicine