As your body ages, you can expect it to undergo gradual changes, at its own pace. How your body ages depends in part on your family (genetic) patterns of aging. However, your lifestyle choices have a more powerful impact on how well your body ages. Fortunately, you can control your lifestyle choices.

The following are normal signs of aging. Some of these changes may apply to you; others may not. A healthy lifestyle may slow many of these effects of aging.

Skin. With age, the skin becomes less elastic and more lined and wrinkled; fingernail growth also slows. The oil glands gradually produce less oil, making the skin drier than before. You can slow skin aging by using moisturizer and protecting the skin from the sun with sunscreen and sun-protective clothing.

Hair. It's normal for hair to gradually thin on the scalp, pubic area, and armpits. As hair pigment cells decline in number, gray hair growth increases.

Height. By age 80, it's common to have lost as much as 2 in. in height. This is often related to normal changes in posture and compression of joints, spinal bones, and spinal discs.

Hearing. Over time, changes in the ear make high-frequency sounds harder to hear and changes in tone and speech less clear. These changes tend to accelerate after age 55.

Vision. Most people in their 40s develop a need for reading glasses as the lens becomes less flexible. It's also normal for night vision and visual sharpness to decline, while glare increasingly interferes with clear vision in the later years.

Bones. Throughout adulthood, bones gradually lose some of their mineral content, becoming less dense and strong. In women, bone loss increases after menopause. You can slow natural bone loss and reduce your risk of osteoporosis by getting regular, weight-bearing exercise (such as walking), taking daily calcium and vitamin D, and avoiding lifestyle choices that weaken bones (such as too much caffeine or carbonated beverages). Your health professional may also recommend a bone-protecting medication. For more information, see the topic Osteoporosis.

Metabolism and body composition. Over time, the body typically needs less energy, and your metabolism slows. Hormone changes in the aging body result in a shift to more body fat and less muscle mass. The best approach to managing these changes is to take in fewer calories while keeping up or increasing your physical activity. Strength training is an especially good way to build or keep your muscle mass.

Brain and nervous system. Starting in the third decade of life, the brain's weight, the size of its nerve network, and its blood flow decrease. But the brain adapts to these changes, growing new patterns of nerve endings. Memory changes are a normal part of the aging process-it's common to have less recall of recent memories and to be slower remembering names and details. You can help keep your brain sharp with regular social activity; "mental exercise," such as doing crossword puzzles and reading; and physical activity, which increases blood and oxygen flow to the brain.