Bone mineral status in adolescent girls: Effects of eating disorders and exercise

Purpose: To compare whole-body, lumbar, total spine, and pelvis bone minera l density (BMD), body mass index (BMI), body composition, energy expenditur e for physical activity, and dietary intake of adolescents, aged 16-22 year s. Methods: Three study groups included 25 girls with histories of eating diso rders, 25 girls with no histories of eating disorders who exercised less th an or equal to 7 hours/week, and 15 girls with no history of eating disorde rs who exercised > 7 hours/week. Bone mineral density was measured by dual- energy x-ray absorptiometry (DEXA), body composition by bioelectric impedan ce and DEXA, energy expenditure by Personal Activity Computer, nutrient int ake by 4-day dietary recalls/records, and BMI by measures of height/weight. General linear models, LSM +/- SEM, Student's t-tests, and correlation ana lyses were used to determine group differences. Results: No significant differences in whole-body, spinal, and pelvis BMD w ere found among the three groups. Mean body fat (percent) was significantly higher (p = .0001) for the group with histories of eating disorders than o ther groups. Dietary intakes of adolescents with histories of eating disord ers were significantly lower for energy (p = .0001), fat (p = .0001), calci um (p = .0007), vitamin D (p = .0180), and zinc (p = .0057) than those with out eating disorder histories who exercised less than or equal to 7 hours/w eek. Conclusion: Except for body fat (percent), measures of BMD, energy expendit ure, and BMI were not significantly different among groups. Our data sugges t that with full recovery from eating disorders, teenage girls can achieve normal bone mass and body composition. (C) Society for Adolescent Medicine, 2000.