Osteoporosis is the loss of bone density or thinning of the bones. This thinning causes bone weakness, and eventually the involved bone may break.
Bones go through a constant state of bone loss and regrowth.
People reach their peak bone mass by about age 30. After the age of 30, bone loss slowly begins to occur. This loss, if it becomes severe, can lead to osteoporosis. The bones become thin and fragile and may break easily. Initially, bone loss occurs very slowly for both women and men.