Dateline: April 30

Nearly 1 in 5 children in America are obese and parents are being urged to pursue radical treatment options.

Tonight on Dateline, Kumi Taguchi meets the kids who have had life altering bariatric surgery at age 12.

Obesity has long been linked to diet, exercise, and socio-economic factors. But recent studies point to genetic factors behind rapid weight gain in children.

Lexi has a malfunctioning gene — MC4R — that’s responsible for food intake and weight control. This genetic disorder keeps the brain in a constant state of hunger, which leads to over-eating and obesity.

By 12, Lexi weighed 116kg, around three times more than the average American girl her age. At school, she says, she was bullied and judged for her size.

“Kids have sent me pictures of food and told me don’t eat my phone and stuff like [that]. It’s really bad,” she said. “Kids sent some death threats, telling me to kill myself and [that] nobody would miss me.”

Seeing her daughter struggle, Brandy started looking into treatments for childhood obesity and came across bariatric surgery.

“I was so terrified that she was going to end up one of those 600-pound people by the time she was 20, and the detriment to her health that that would have on her,” Brandy said.

“I was scared that I was going to outlive this child. And I knew that we had to do something different.”

9:30pm Tuesday on SBS.