Reciprocal regulation of bone and energy metabolism.

The finding that fat regulates bone metabolism was viewed as an indication that bone might regulate some aspects of energy metabolism in a feedback loop. The search that started nine years ago for a bone-derived hormone that regulates energy metabolism first took a convoluted path through the identification of a modifier gene. Once this hormone, osteocalcin, was identified, it became clear that bone exerts a profound and complex influence on glucose and fat metabolism. This review highlights the most important salient features of this novel regulation of energy metabolism.