PHOENIX - Imagine having to lock the pantry and refrigerator doors after each meal because you can't control how much you eat.
It's an every-day occurrence for one Phoenix family and they're telling their story Friday night on ABC's "20/20".
Hannah Wilkinson, a 14-year-old girl, weighs 340 pounds despite exercising and eating around 1,000 calories a day, according to her mother, Tonya.
Hannah has Prader-Willi syndrome, and Tonya documents a strenuous and strict daily diet and exercise routine for ABC News.
According to Tonya, each day for Hannah starts early and hungry, so she makes her a healthy and low-calorie meal. Just a few minutes later, Hannah is hungry again, but she has to wait an emotional and difficult few hours for a small snack.
Hannah has been caught eating garbage and dog food in order to satiate her appetite.
ABC News says one in 15,000 people struggle with Prader-Willi syndrome, a chromosome flaw that affects the brain's hypothalamus area, as well as metabolism, learning and muscles.
“The hypothalamus, the part of our brain that controls our hunger, with children or adults with Prader-Willi Syndrome, is pretty much shut off, so they don't know that they're not hungry,” Tonya told ABC.
Hannah's life is consumed by the need to eat each and every day. Her mother worries that if she doesn't get help or get to the bottom of the issue, she could die.
To learn more about Hannah and Prader-Willi syndrome, tune in to ABC's "20/20" Friday night at 9 p.m.