Percentage changes (Mean ± SE) in body composition by group assignment over the 4 years. BMI: body mass index, TrF: trunk fat, TrL: trunk lean, PTrF: percentage of trunk fat. Δ: percentage change, equals (Follow-up - Baseline)/Baseline * 100. Ca-only: calcium group; Ca + D: calcium plus vitamin D group; Placebo: placebos group. At baseline (year 0): Placebo (n = 206), Ca-only (n = 328), Ca + D (n = 336); at year 1: Placebo (n = 191), Ca-only (n = 310), Ca + D (n = 310); at year 2: Placebo (n = 187), Ca-only (n = 300), Ca + D (n = 298); at year 3: Placebo (n = 189), Ca-only (n = 287), Ca + D (n = 296); at year 4: Placebo (n = 178), Ca-only (n = 274), Ca + D (n = 297). The P values were calculated by analysis of covariance (ANCOVA) at each follow-up measure (time point). A general linear model (GLM) was used with phenotype changes as dependent variables, treatment as an independent variable, age, season, and estrogen use (stepwise multiple regression P < 0.05) as covariates. The significant covariates in the model were as follows: at year 1: season; at year 2: age, season, and estrogen use; at years 3 and 4: age and estrogen use.