LA CROSSE, Wis. (WKBT) -

Childhood obesity rates have more than doubled over the past 15 years, according to a new study by JAMA Pediatrics. The Centers for Disease Control said that in 2012, more than one-third of children and adolescents were overweight or obese.

According to the CDC, 18 percent of American children ages 6-11 are obese. In La Crosse County's Women Infants and Children program, about 30 percent of children ages 2-5 are overweight or obese, which is the average across Wisconsin.

The growing number of overweight children has changed the nation's view on obesity, and that extra weight is causing medical issues later in life.

"We have reset our fatness look in the United States. So we think kids that are really pretty heavy are actually pretty normal. So that whole problem starts in that we really don't know what you're supposed to look like anymore," Dr. CJ Menagh, a pediatrician at Mayo Clinic Health System, said.

Over Menagh's 30 years of practicing medicine, he said he's seen the number of overweight children grow incredibly fast.

"Now it's incredibly common. We're seeing more of these children with high blood pressure, with diabetes problems, with difficulties with their joints, with what we call metabolic syndrome," Menagh said.

Menagh said these are diseases that are expected in adults in their 50s and 60s, not in children.

Menagh said that since the idea of being overweight has changed, it will be hard to change back.

"It's going to be a really hard thing to do, to reset people's perceptions of what is normal," Menagh said.

In La Crosse County, there are staff members dedicated to bringing down the number of overweight kids.

"We are definitely a very active county," Jennifer Miller, registered dietitian for La Crosse County, said.

Miller said establishing healthy habits in adults leads to healthier kids.

"We're working with those pregnant women right away and teaching them good nutrition for themselves while they're pregnant, but we're also helping with those babies, and then as they grow, that proper nutrition," Miller said.

Miller said getting kids to eat healthy and be active at a young age will instill a healthy lifestyle for the future.

"It's just the balance. Healthy eating, physical activity, healthy beverages and not focusing on that number. Not focusing on that weight all the time or that BMI," Miller said.

Miller said La Crosse County works with all school districts in the county to get healthy foods at lunchtime, and a program working with La Crosse schools is getting kids to be active after sitting during class.

Mayo Clinic Health System is developing a program to actually prescribe physical activity to overweight patients. It will include text reminders to be active and advice on exercise programs and healthy eating choices.