BALTIMORE -- You've heard it many times before that childhood obesity is becoming an epidemic.

CHILDHOOD OBESITY Calculate: Child's BMI Survey: Kid With Weight Problem? FROM OUR PARTNERS Hub: About Kids' Nutrition About: Child Obesity Link: Get Kids Off Couch

In 2002, roughly 15 percent of American teens were heavy enough to be obese, according to the Centers for Disease Control and Prevention. What can be done to battle the bulge in younger populations?

The University of Maryland School of Medicine received federal funding to create and evaluate the Challenge Project, a program to prevent obesity by helping teens learn to make healthy dietary and physical activity choices for themselves.

"Not much works in fighting obesity," said Dr. Maureen Black, an expert in growth and nutrition at the University of Maryland Hospital for Children. "The best solution is to prevent obesity in the first place through diet and physical activity."

Black said they hospital began the project by forming an advisory board of teens from West Baltimore.

"(The teens) told us that they wanted personal trainers to help them work on diet and physical activity," Black said. "We recruited young adults from several local colleges and trained them to serve as mentors. We hooked up kids who were ages 11 to 14 with mentors who served as personal trainers."

The mentors and teens in the Challenge Project meet weekly to work on activities and to learn to create goals. They learn to challenge themselves.

For instance, several teens decided that instead of drinking four or five sodas a day, they would drink one soda and incorporate water into their diets. Other teens decided that they would walk at least 2 miles every day. The program gives pedometers to all the teens.

The important component of the Challenge Project is that the teens are setting their own goals and learning to evaluate their progress.

"The mentors and kids go to fast-food restaurants and corner stores to determine what healthy choices they could make when eating there," Black said. The mentors serve an important role to help the teens feel empowered about the choices they are making, she said.

Many of the teens in the program are reaping the rewards. It is important to remember that healthy habits, like eating well and being physically active, are instilled during childhood and adolescence.