NASHVILLE, Tenn. (Ivanhoe Newswire) -- We've all heard about the obesity epidemic in America, and it's hitting kids before they even learn how to walk and talk. Statistics show one in five 4-year-olds is considered obese. Doctors say parents can turn the trend around by knowing how much is too much when it comes to the bottle.

Kathy Magallanes is learning the ropes of motherhood for a second time.

"It's been a long time since I've been responsible for a little bitty baby, and I know things have changed," Magallanes told Ivanhoe.

This grandmother is raising her granddaughter. Whenever Macie cries…

"Oh, that baby's hungry," Magallanes explained. "I don't want her to be hungry, and I'll give her a bottle,"

"If you constantly feed babies when they're young, they actually lose their ability to sense fullness," Russell Rothman, M.D., M.P.P, an assistant professor in internal medicine and pediatrics at Vanderbilt University Medical Center in Nashville, Tenn., told Ivanhoe. "They may become more likely to be an overeater as they get older."

More than 500,000 4-year-olds are obese. Weight in the first two years can be predictive of how much weight they'll gain later.

"The most common vegetable for the toddler is currently the French fry," Dr. Rothman said.

Babies don't need juice. If you give it to them, dilute it. For solids: fewer crackers and cookies.

Know when the baby is full. She may keep her mouth closed, push the bottle away or start falling asleep.

"Try to recognize what is their hungry cry versus when they're really crying because they're wet or for some other reason," Dr. Rothman said.

Babies can also exercise. It's called tummy time.

"Learning to push themselves up," Dr. Rothman explained. "Learning to crawl and really get more mobile even at a young age."

Magallanes wants to change her habits.

"My family, we have a lot of diabetes, and he said we got to watch that, and we don't want to feed her too much," she told Ivanhoe.

Overweight children aren't just a problem in this country. Nearly half of the children in North and South America will be overweight by next year, according to a report in the International Journal of Pediatric Obesity.