Osteoporosis, which means "porous bones," causes bones to become weak and brittle — so brittle that a fall or even mild stresses like bending over or coughing can cause a fracture. In many cases, bones weaken when you have low levels of calcium and other minerals in your bones. A common result of osteoporosis is fractures — most of them occur in the spine, hip or wrist. Although it's often thought of as a women's disease, osteoporosis affects men too. And aside from people who have osteoporosis, many others have low bone density, putting them at risk of developing osteoporosis. Scientists don't yet know exactly why osteoporosis occurs, but they do know that the normal bone remodeling process is disrupted. Your bone is continuously changing — new bone is made and old bone is broken down (resorption) — a process called remodeling or bone turnover. When you're young, your body makes new bone faster than it breaks down old bone and your bone mass increases. You reach your peak bone mass around age 30. After that, bone remodeling continues, but you lose slightly more than you gain. How likely you are to develop osteoporosis depends on how much bone mass you attained in your 20s and early 30s (peak bone mass) and how rapidly you lose it later. The higher your peak bone mass, the more bone you have "in the bank" and the less likely you are to develop osteoporosis as you age. The strength of your bones depends on their size and density; bone density depends in part on the amount of calcium, phosphorus and other minerals bones contain. When your bones contain fewer minerals than normal, they're less strong and eventually lose their internal supporting structure. Other factors, such as hormone levels, also affect bone density. In women, when estrogen levels drop at menopause, bone loss increases dramatically. In men, low estrogen and testosterone levels can cause a loss of