The problem is video games, smart phones and computers. Kids are supposed to get an hour of exercise each day but 50% of boys and 75% of girls ages 12-19 are not.
Kelsey-Seybold Dr. Hunaid Gurji says there are multiple factors in the lack of teen exercise.
"It's not just schools changing their curricula; it's not just new technology that we have."
Therapist and teen expert Lori Vann says parents need to explain the consequences of a sedentary lifestyle.
"And that way it's not being judgmental from the onset; it's not being an ogre, it's giving them an opportunity to have a conversation with you."
Vann says parents have to set time limits for game playing and computer use.
"And before they get a cell phone there needs to be a contract of 'this is the expectation, these are the guidelines, and these are the rules' and there should be time limits."
Dr. Gurji says the kids may not be eating right, either.
"It's not just a factor of physical activity it's also healthy eating, making the right decisions when it's time to have meals and snacks."
As a result American kids are some of the fattest in the world.