Relationship between underweight, bone mineral density and skeletal muscle index in premenopausal Korean women

Osteoporosis and sarcopenia are common health problems in postmenopausal women. However, studies of these issues in premenopausal women are limited. Our present study aimed to investigate relationship the between underweight, bone mineral density (BMD) and skeletal muscle index (SMI) in a representative sample of premenopausal Korean women.

We used data from the Korea National Health and Nutrition Examination Surveys (2009-2010). Participants included 1767 healthy, ≥ 20-year-old, non-obese premenopausal women. Underweight was defined as BMI< 18.5 kg/m(2) and normal weight was defined as 18.5 ≤ BMI< 23 kg/m(2) . We analysed anthropometric measurements, BMD and SMI with a DXA scanner. Multiple logistic regression analysis was performed to assess the relationship between underweight, BMD and SMI after adjusting for confounding factors.

The prevalence of low BMD and low SMI in underweight women was 23.9% and 18.4%, respectively, compared with 9.4% and 1.7% in normal weight women. Low BMD and/or low SMI were present in 36.7% of underweight women compared with 10.7% of normal weight women. After adjustments, underweight women exhibited a higher odds ratio for low BMD (OR, 3.41; 95% CI, 2.31-5.05), low SMI (OR, 11.61; 95% CI, 6.17-21.88) and combined low BMD and low SMI (OR, 23.82; 95% CI, 8.92-63.58) when compared with normal weight women.

Underweight premenopausal women are at a higher risk of low bone mass and low skeletal muscle. Educational efforts that promote a normal weight in premenopausal women should be reinforced.