How Does Osteoporosis Occur?

Osteoporosis, or bone loss, occurs when the process  of bone breakdown and bone formation gets out  of balance. The cells that cause bone breakdown (osteoclasts) start to make canals and holes in the bone faster than the cells that cause bone formation (osteoblasts) can make new bone to fill in the holes. The bone becomes fragile and more likely to break. When bone has to give up some of its calcium to ensure that blood levels of calcium stay normal, bone is weakened by the loss of calcium. The weakening of bone by its loss of calcium also leads to osteopenia and osteoporosis.

Taking in extra calcium and vitamin D alone will not prevent osteoporosis. Because of the way bone develops, the mechanical stress on bone caused by exercise is also important for preventing osteoporosis. The less you exercise, the less the osteoblasts work to make new bone. You need both weight-bearing and  resistive exercise to promote strong bones .

When the body has not formed adequate bone during childhood and young adulthood, the lack of bone mass is also termed osteoporosis or osteopenia, depending on how frail the bones are. Even if your bones are not so frail that you have osteopenia or osteoporosis, not reaching peak bone mass in your youth makes osteoporosis more likely to occur. The reason that building strong bones in childhood is so important is that if a young adult does not have peak bone mass, osteoporosis is more likely to develop despite preventive measures taken later in life.