In this topic you will learn about how your appearance and behavior change as you grow.

All living things have a life cycle, which includes infancy, childhood, adolescence, and maturity. During infancy you needed an adult to feed you, protect you, and make sure you were warm enough. During childhood your mental growth continued to expand. When you were about five years old, you reached almost half of your adult height.

Adolescence is the period of time between childhood and adulthood. It begins at puberty. A girl's ovaries begin to release eggs, and a boy's testes start producing sperm. Hormones cause the body to grow quickly.

Your bones will stop growing when you are between 18 and 22 years of age. For the next 20 years or so, your body will work at its peak. Then you may notice hairs turning gray, muscles aching, and wrinkles beginning to appear.

Most women go through menopause between ages 40 and 55. Menopause is the time in life when a woman's ovaries stop releasing eggs. She can no longer have children and many of her hormone levels fall. Often her bones become thin and brittle. Most men lose more and more of their hair as they age. Their muscles weaken and decrease in size.

Many elderly people come down with serious and life-threatening conditions, such as heart disease and cancer. However, many live long, healthy lives, without getting seriously ill.

The food you eat contains nutrients. A nutrient is any of the substances in food that the body needs to grow, develop, work at its best, and stay healthy. Nutrients include proteins, carbohydrates, fats, vitamins, minerals, and water. Your body also needs fiber, fruits, and vegetables. Foods rich in proteins, minerals, and vitamins are important at every stage of life. All people should be careful about what they eat. Foods high in fat and added sugars can help cause cancer and heart disease later on in life.

The Food Guide Pyramid is a chart that organizes food into five groups that supply the body with nutrients. The bigger the section of each food group, the more servings you should eat from it. At the top of the pyramid are foods high in fats and added sugars. You should limit these foods in your diet because they will put unhealthy weight on your body and put you at risk of disease as you grow older.