The number of obese children has tripled since the 1980s but health experts say lifestyle changes can reverse this U.S. health epidemic.

Today, one in five children is obese, and as a result, they are nearly certain to have serious medical problems in the future, like heart disease, diabetes, and cancer.

"If you look at children who are overweight at the ages of ten to 12, 80 percent of those children will become overweight adults," pediatrician Dr. Robert Fink said.

"And so we've got to intervene on these children before they hit teenagers. We've got to intervene at the earliest age, so we can pick em up," he added.

In an effort to combat the epidemic, first lady Michelle Obama launched her "Let's Move" program, and celebrity chef Jamie Oliver convinced some school districts to lighten their lunches.

While those are steps in the right direction, a child's best chance for reaching and maintaining a healthy weight is when their parents are on board.

"I would say that the majority of children that we see in the office who are overweight have overweight parents. And it becomes an issue that we're trying to treat the whole family," Fink explained.

Doctors recommend every family member observe the same rules. The rule of no eating should be enforced while watching TV, playing video games, or surfing the Internet.

Parent should also limit any screen time to one hour a day.

They should also decrease the amount of fried food the family eats and give up fast food entirely.

Food portions should become smaller and the number of portions should be also decreased, while increasing daily exercise.