Table 5. Multivariate-adjusted odds ratios of the presence of underweight participants at 20 years old and/or osteopenia among women with BMI less than 25.0 kg/m2.
| At 20 years old | ||||
| Normal weight | Underweight | |||
| Present | ||||
| Normal weight | Underweight | Normal weight | Underweight | |
| Group 1 | Group 2 | Group 3 | Group 4 | |
| n | 458 | 74 | 100 | 51 |
| Osteopenia (%) | 182 (39.7) | 42 (56.8) | 33 (33.0) | 27 (52.9) |
| OR (95% CI) | ||||
| Model 1 | ref | 2.64 (1.49–4.67) | 0.79 (0.47–1.34) | 3.57 (1.77–7.19) |
| Model 2 | ref | 2.73 (1.53–4.87) | 0.80 (0.46–1.38) | 3.66 (1.82–7.39) |
| Additional model | — | — | ref | 3.83 (1.56–9.41) |
CI, confidence interval; OR, odds ratio.
Normal weight: BMI 18.5–24.9 kg/m2, Underweight: BMI <18.5 kg/m2.
Osteopenia: T score less than −1 standard deviation.
Model 1: Adjusted for age.
Model 2: Adjusted for age, postmenopausal years, taking calcium supplement, walking time per day, smoking habit, drinking habit, milk or yogurt intake and hyperthyroidism.
Additional model: Participants with normal weight at 20 years were excluded, and the logistic regression model was adjusted for model 2 variables.