Many teens live in perfect situations to pack on pounds: access to high calorie foods and limited opportunities for exercise. But for some D.C. teens who want to live healthier lifestyles, making the change requires overcoming greater challenges.

Four out of every 10 D.C. public school students are overweight or obese. The D.C. City Council passed the Healthy Schools Act as a way to tackle the problem.

Children's National Medical Center's I.D.E.A.L. Clinic works with the most obese children in the District. And although I.D.E.A.L. stands for "Improving Diet, Exercise and Activity for Life," one of the clinic's doctors points out that overcoming the challenges of childhood obesity can involve a lot more than just diet and exercise.

Scientists are still trying to understand the causes of childhood obesity and how best to treat it. Researchers in the area are attacking the problem in a number of different ways: examining environmental influences, genetic triggers, psychological reasons, new medicines, and even epi-genetics, which looks at how the prenatal environment influences genes.

One in every three children in the United States is overweight or obese, with significant numbers facing health problems such as heart disease, high blood pressure and diabetes. But how do these national statistics play out in a family? The Freedmans from Olney, Md., say knowing their daughter had a problem was the easy part -- getting help was quite another.

WAMU education reporter Kavitha Cardoza and co-producer Ginger Moored reflect on what they learned from their five-part childhood obesity series.

Kelly Sinclair, a clinical dietitian at Children's National Medical Center, spoke with WAMU's Kavitha Cardoza for her five-part series, "The Heavy Burden of Childhood Obesity." Here are a few of the weight-loss tips she has for children: