A number of factors increase the risk of developing osteoporosis. They include:

• Age. Osteoporosis is more likely as people grow older and their bones lose tissue.
• Gender. Women are smaller and start out with less bone. They also lose bone tissue more rapidly as they age. While women commonly lose 30–50% of their bone mass over their lifetimes, men lose only 20–33%.
• Race. Caucasian and Asian women are most at risk for the disease, but African American and Hispanic women can get it too.
• Figure type. Women with small bones and those who are thin are more liable to have osteoporosis.
• Early menopause. Women who stop menstruating early because of heredity, surgery or lots of physical exercise may lose large amounts of bone tissue early in life. Conditions such as anorexia and bulimia also may lead to early menopause and osteoporosis.
• Lifestyle. People who smoke or drink too much, or don't get enough exercise have an increased chance of osteoporosis.
• Diet. Those who don't get enough calcium or protein may be more likely to have osteoporosis. That's why people who constantly diet are more prone to the disease.
• Genetics. Research in Europe reported in 2003 that variations of a gene on chromosome 20 might make some postmenopausal women more likely to have osteoporosis. Studies were continuing on how to identify the gene and use information from the research to prevent osteoporosis in carriers.

Osteoporosis is often called the “silent” disease, because bone loss occurs without symptoms. People often don't know they have the disease until a bone breaks, frequently in a minor fall that wouldn't normally cause a fracture. A common occurrence is compression fractures of the spine. These can happen even after a seemingly normal activity, such as bending or twisting to pick up a light object. The fractures can cause severe back pain, but sometimes go unnoticed--either way, the vertebrae collapse down on themselves, and the person actually loses height. The hunchback appearance of many elderly women, sometimes called “dowager's” hump or "widow's" hump, is due to this effect of osteoporosis on the vertebrae.