Context: Consolidation and maintenance of peak bone mass in young adulthood may be compromised by inactivity, low dietary calcium, and diet-induced weight loss.
Objective: We aimed to determine whether higher intakes of dairy foods, dietary calcium, and protein during diet- and exercise-induced weight loss affected markers of bone health.
Participants: Participants included premenopausal overweight and obese women.
Design/intervention: Ninety participants were randomized into three groups (n = 30 per group): high protein and high dairy (HPHD), adequate protein and medium dairy (APMD), and adequate protein and low dairy (APLD), differing in dietary protein (30, 15, or 15% of energy, respectively), dairy foods (15, 7.5, or <2% of energy from protein, respectively), and dietary calcium (∼1600, ∼1000, or <500 mg/d, respectively).
Outcome measures: Serum and urine bone turnover biomarkers, serum osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL), PTH, 25-hydroxyvitamin D, leptin, and adiponectin measured at 0 and 16 wk.
Results: All groups lost equivalent body weight (P < 0.05). N-telopeptide, C-telopeptide (CTX), urinary deoxypyridinoline, and osteocalcin increased in APLD (P < 0.01), whereas in HPHD, osteocalcin and procollagen 1 amino-terminal propeptide (P1NP) increased (P < 0.05), and all resorption markers remained unchanged. P1NP to CTX and OPG to RANKL ratios increased in HPHD (P < 0.005), and P1NP to CTX ratio decreased in APLD (P < 0.05). PTH decreased in HPHD and APMD vs. APLD (P < 0.005), and 25-hydroxyvitamin D increased in HPHD (P < 0.05), remained unchanged in APMD, and decreased in APLD (P < 0.05). Leptin decreased and adiponectin increased in APMD and HPHD only (P < 0.001).
Conclusions: Hypoenergetic diets higher in dairy foods, dietary calcium, and protein with daily exercise, favorably affected important bone health biomarkers vs. diets with less of these bone-supporting nutrients.
Trial registration: ClinicalTrials.gov NCT00710398.