Bone is usually removed and replaced in response to the stresses placed on it by daily activities. The female hormone estrogen helps to control the amount of bone that is lost. The amount of bone that you will accumulate in your lifetime (the "peak bone mass") is acquired during childhood and early adulthood and is slowly lost after that.

Bone is lost more quickly after menopause. The earlier that menopause occurs, whether naturally or due to treatments such as chemotherapy, radiation therapy, or hormone medications, the more bone is eventually lost. A similar circumstance occurs in men. The male hormone testosterone helps your body make more bone. When less testosterone is available, such as may occur with aging or with some treatments for prostate cancer, the amount of bone you have slowly declines.

Bone is organized to be strong enough to allow you to do normal activities, such as standing, walking, and running, and is typically strong enough to withstand small additional stresses, such as falls from a sitting or standing height. If you have broken ("fractured") a bone as a result of a fall while sitting, standing, or walking (defined as a "fragility fracture"), this may indicate that your bone is not as strong as it should be. These fractures are frequently the first indication that you have low bone mass (osteopenia or osteoporosis). Broken bones as a result of higher energy events, such as motor vehicle collisions or sports accidents, usually don't indicate a problem with your bones.

There is evidence that the risk of developing osteoporosis may be inherited in some people. Both women and men may have family members with osteoporosis. If you have someone in you family with osteoporosis, should be even more aware of taking care of bones with appropriate diet and adequate exercise.

Osteoporosis does not cause any symptoms, until you break a bone. Broken bones, especially those that happen after a fall while standing or walking, are frequently the first indications that you or a family member has osteoporosis. Although you may not know if a family member has been diagnosed with osteoporosis, if someone in your family has sustained fractures, especially of the hip, spine, or wrist, this may indicate that you have an inherited risk of developing osteoporosis.

Although any bone can break if it is weakened by osteoporosis, the most common places to break a bone are the spine, hip, and wrist. Broken bones in the spine can occur with minimal activity, such as a fall or while lifting. Broken bones in the spine can lead to chronic back pain. Several broken bones can cause the spine to start to collapse, leading to a loss of height. It is helpful to keep track of your height, to identify any loss early.

Chemicals absorbed while smoking can slow down the cells that make bone. Since the cells that remove usually remove bone are unaffected, this can lead to a gradual loss of bone.

Bone remains strong when it is used, such as with weight-bearing exercise. These exercises stimulate your body to make more bone. Although other exercises, such as swimming and biking, are good for your heart and lungs and don't put much stress on your joints, they don't contribute much to maintaining strong, healthy bones. Weight-lifting may make the bone adjacent to the muscles being used stronger and may make you strong enough that you are less likely to fall, it doesn’t maintain the strength of all of your bones, as does weight-bearing exercise.

An exercise regimen should ideally include weight-bearing exercise for bone, heart, and lung health and weight-lifting to improve strength and decrease the chances of injury-producing falls. Swimming and biking can be added for those who have joint conditions, such as arthritis, that keep them from doing much weight-bearing exercise, as long as you realize that this won’t provide much protection for your bones. Balance exercises, such as tai chi, have also been found to be helpful by decreasing the risk of falls and broken bones.

Calcium is the primary mineral that makes bones strong. This calcium is acquired through your diet. Vitamin D is necessary to help you absorb calcium. The amount of both of these nutrients depends on your age. See the linked chart for the daily recommended amounts. Look at food labels or other materials to find out how much calcium and vitamin D you are currently taking in. Although vitamin D can be made by your skin as a result of exposure to the sun, the amount that is made varies based on the time of year, how much time you spend in the sun, and how much of your skin is exposed. In addition, excessive sun exposure can result in the development of skin cancer. Adequate calcium and vitamin D intake may require the use of supplements.

Several chronic medical conditions can affect bone. These can affect bone either by decreasing the amount of bone made, the amount of bone lost, or the amount of mineral in the bone. Almost every organ in your body has an impact on the health of your bone.

Chronic medical conditions can affect bone either because of the changes in the way a specific organ works or as a result of the treatment of these conditions. Oral steroids (glucocorticoids) are the most common medications that lead to osteoporosis, especially if taken daily for three months or more. However, many other medications can affect bone, either by slowing down how fast bone is made or increasing the amount of bone that is removed.