When teenagers have stick-thin celebrities as role models, it's easy for them to lose sight of a healthy body image. If the average female television or movie star is a size zero, a teenager who is a size four might compare her body to the one that she sees on the TV and feel, well, large.

In reality, the average American female is a size 12 of 14. Judging by those standards, a size 10 is relatively skinny. With that said, size doesn't really matter. In fact, a person who is a size 10 may be healthier than her size four counterpart! It's nearly impossible to determine whether a person is overweight, obese or morbidly obese just by comparing the tags on her jeans.

What does matter is your Body Mass Index (BMI). The BMI is a measurement that tells you what your body fat percentage is through a calculation of your height and weight. If your BMI is in the 25-29.9 range, a doctor will consider you to be overweight. If it is over 30, you are obese. People who have a BMI of 50 or higher are morbidly obese, and have a 50 percent greater risk of death than those who are of a healthy weight.

Having too much body fat can definitely be hazardous to your health. Some of the common risks associated with being overweight or obese include diabetes, heart disease, stroke, cancer, osteoarthritis and gall bladder disease.

Although it is unlikely that an overweight teen will suffer from these health problems, it is important to address the weight issue before they arise. Learning to eat healthier and move around more are key components to maintaining a healthy body weight. Plus, people who eat right and work out generally feel better about themselves which can go a long way toward improving your body image.