Cao discusses the study of Sharma et al in which they investigated the acute changes in concentrations of the circulating bone resorption marker, C-terminal cross-linking telopeptide of type 1 collagen (CTX), in response to either calcium in the form of high-calcium skim milk or calcium carbonate in a randomized crossover study design with 77 nonoverweight and overweight or obese postmenopausal women. The finding from Sharma et al that circulating concentrations of CTX in overweight or obese postmenopausal women are similarly responsive to dietary calcium intake compared with nonobese women has important implications for bone metabolism. Most forms of bone loss reflect increased bone resorption relative to bone formation, especially in postmenopausal women, who are susceptible to bone loss due to the decrease in estrogen after menopause.