An interim analysis of the influence of eating disorder risk, body dissatisfaction, physical activity, and diet on bone mineral density in college-aged females

TL;DR

This study found that college-aged females with low bone density often have poor physical activity levels, but not necessarily due to eating disorders or diet.

Contribution

The study identifies physical activity as a key factor influencing bone mineral density in young women, independent of eating disorder risk or diet.

Findings

47–65% of participants had low bone mineral density (BMD) z-scores at multiple body sites.

Total hip BMD z-scores were positively correlated with physical activity metrics like daily steps and moderate activity.

No significant associations were found between BMD and eating disorder risk, body dissatisfaction, or dietary intake.

Abstract

This study aimed to examine relationships between BMD z-scores, eating disorder (ED) risk, body image dissatisfaction (BID), physical activity, and dietary intake in college females.

College-aged females (n = 20, age: 19 ± 1 yrs, weight: 58 ± 9 kg, BF%: 29 ± 6%) participated in this cross-sectional study. Whole body, total hip, femoral neck, and lumbar spine BMD were assessed using dual-energy x-ray absorptiometry. Participants completed validated questionnaires to assess ED risk and BID. Objective physical activity (daily steps, daily physical activity energy expenditure (PAEE), time spent in sedentary (PAs), light (PAL), moderate (PAM), and vigorous (PAV) zones), and dietary intake were quantified across 3-days via a wrist-worn accelerometer and a self-reported food log, respectively. Spearman correlations evaluated relationships between BMD, ED scores, BID, physical activity metrics, and dietary intake (p < 0.05).

47–65% of participants had low BMD (z-score < 0) at whole-body, hip, and spine sites, with 40% classified as osteopenic (Ta ble 1). Additionally, 20% were at risk of ED and 65% conveyed BID. Participants averaged 15,789 ± 4,116 daily steps, expending 986 ± 396 active calories. Total hip BMD z-scores were positively associated with daily steps (r = 0.462, p = 0.046), PAEE (r = 0.493, p = 0.032), and PAM (r = 0.575, p = 0.010). No other relationships were observed between BMD, ED risk, BID, and dietary intake (calories, carbohydrates, protein, fat, calcium) (p > 0.05).

A high incidence of low BMD was observed across all sites (whole body, total hip, femoral neck, and lumbar), with BMD z-scores associated with physical activity (daily step counts, PAEE, and PAM), but not with dietary intake, ED risk, or BID. These findings highlight the importance of physical activity for maintaining bone health in premenopausal females. As BMD reflects long-term bone health, it may not capture acute dietary or lifestyle changes, highlighting the need to assess dynamic bone turnover markers.

Full text

Table 1.Body composition, bone mineral density (BMD) z-scores, and prevalence of negative BMD z-scores. BMD z-Score(95% CI)% of Participants with Low BMD(z-score < 0)% OsteopeniaWhole Body0.1 ± 1.0(−0.4,0.6)65% (n = 13)10% (n = 2)Total Hip0.1 ± 1.0(−0.4,0.7)47% (n = 9)16% (n = 3)Femoral Neck0.1 ± 1.2(−0.5,0.6)53% (n = 10)21% (n = 4)Total Lumbar Spine−0.1 ± 1.1(−0.6,0.4)65% (n = 13)30% (n = 6)Values are mean±SD (95% CI).