Overweight Girl Mystifies Family

Despite a restricted diet, a regular exercise program and the anxious scrutiny of her parents, doctors and state officials, 4-year-old Anamarie Martinez Regino remains very big for her age.

Last August, when she was only 3 years old, Anamarie weighed 120 pounds — more than three times that of an average toddler.

At her doctor's recommendation, the New Mexico Children, Youth and Families Department took the girl away from her family, saying her life was in danger because her family could not control her weight.

At the time, a state social worker said the girl would die unless she followed a special diet, exercised more and used a breathing machine when she slept.

Strict Diet and Exercise

Today Anamarie is back home and her parents are keeping her on a liquid diet, but they still haven't figured out the cause of her obesity.

She is now 20 pounds slimmer and is able to walk with difficulty. She eats about 900 calories a day and is active, swimming five days a week.

But at 100 pounds and 3 feet, 10 inches, Anamarie remains much heavier and taller than other children her age.

The toddler spent almost four months in foster care, with her parents not knowing her whereabouts at first, while the state tried to find out why she was so drastically overweight.

The girl lost 10 pounds while in state custody, and has continued to lose weight at home. She now sees a doctor every couple of weeks, her mother says.

Her parents want to know why Anamarie is so unusually tall, why her hair is as thick as an adult's and why she has had all of her teeth since she was less than a year old.

Anamarie's mother was forced to quit her job to take care of her daughter. Her husband is on disability because he has diabetes. The family lives on unemployment and Medicaid.

Medical Mystery Grows and Grows

In 1998, doctors thought that Anamarie suffered from Prader-Willi syndrome, a noninherited genetic problem that makes people feel constantly hungry.

Later, the diagnosis was changed to leptin receptor deficiency, a hereditary problem that keeps the brain from sending signals that the body is full, and to stop eating.

But such diagnoses do not explain her rapid growth.

ABCNEWS' Dr. Tim Johnson says there is probably a medical cause for Anamarie's condition, though it may be hard to find.

"When you have this kind of very excessive obesity at a very young age, it is much more likely to be a genetic or metabolic problem than when you have obesity in adulthood," he said.

Johnson says a leading authority on obese kids, Dr. Steven O'Riley, a professor of metabolic medicine at Cambridge in England, is convinced that many obese kids have an underlying genetic or metabolic defect.