(NEW YORK) -- Lu Hao, a three-year-old toddler in China, weighed less than six pounds at birth. But he gained weight rapidly, and today tips the scales at an astonishing 132 pounds -- five times the normal size of a child his age. He's also a medical mystery, with doctors in China unable to diagnose just what's behind the youngster's abnormal weight gain.
"It's obviously an extreme form of obesity," said Dr. Stephen Cook, a fellow in pediatrics at the Golisano Children's Hospital at the University of Rochester. "I don't think I [have] ever seen anything quite like it."
Hao's parents, desperate for medical answers, said forcing him to eat less has been met with drama.
"We have to let him be, as if we don't feed him he will cry non-stop," Hao's mother, Chen Yuan, told Britain's Sun newspaper.
She said Hoa throws angry temper tantrums when they attempt to curtail his massive appetite, which includes devouring huge plates of ribs and rice.
"At some level, the parents are being semi enablers," said Dr. Cook. "It's, of course, extremely difficult to put a child this young on any kind of a diet, but he needs limitations on his intake."
Cook called the condition "partly behavioral" and said the parents will need to set healthy limits on what he should eat.
Hao's severe weight problem is being aided by his aversions to exercise. His parents said he hates walking, so they take him to kindergarten on a motorcycle.
Yet his parents do push him to be more mobile. Though Hao hates walking, he does like swimming. His parents also installed a basketball hoop to encourage him to exercise.
But exercise just makes Hao hungrier and that typically results in him gaining even more weight.
Hao's parents took him to see several specialists in China. Doctors at the Guangdong Children's Hospital told the parents their child's weight gain could be caused by a hormone disorder. Meantime, some experts said the child has signs of Prader-Willi syndrome, a rare genetic disorder that's not very well known to the public or some in the medical field.
Copyright 2011 ABC News Radio