The associations of oral contraceptive use and cognitive dietary restraint with bone speed of sound (SOS) and bone turnover were investigated in 100 Canadian university-aged women (18-25 years old). Dietary restraint was assessed using the Dutch Eating Behavior Questionnaire (DEBQ) and daily calcium intake (Ca++) was assessed by the rapid assessment method. Quantitative ultrasound was used to measure SOS at the tibia and radius. Bone formation was estimated from plasma osteocalcin (OC), 25-OH vitamin D, and serum bone-specific alkaline phosphatase (BAP). Bone resorption was determined from serum cross-linked N-teleopeptide of type I collagen (NTx) and plasma C-terminal telopeptide of type I collagen (CTx). Weekly physical activity energy expenditure (WAeq) was assessed using a standardized questionnaire, and height, body mass, relative body fat (%BF), and chest, waist, and hip circumferences were also measured. Participants were divided into low and moderate to high dietary restrainers (LDRs and MDRs, respectively). These groups were further sub-divided into users and non-users of oral contraceptives. All groups had similar age at menarche, body composition, WAeq, and equally low levels of Ca++ and vitamin D. Within the non-users of oral contraceptives, MDR exhibited a lower tibial SOS (p