For most of us, snacking is a bad habit. For Melissa Moss, a Californian with a rare genetic disorder, it's a matter of life and death. A chromosomal abnormality known as Prader-Willi syndrome has cursed her with both an insatiable appetite and a metabolism so slow that she gains weight eating just 1,600 calories a day.
Moss, an articulate 28-year-old, used to steal leftovers from cafeteria trays when she was in elementary school, or even pick scraps off the floor. Now that she's an adult, food is never far from her mind. She spends hours every day counting calories, weighing and reweighing foods, and figuring out, down to the last half pretzel, how much she can eat. Her 1,300-calorie-a-day diet of yogurt, fruit, fat-free turkey sandwiches, and diet TV dinners is spartan and monotonous, but it has kept her slender, and alive. Untreated, most people with the syndrome become obese by their teenage years and are dead by adulthood, killed by heart disease, diabetes, or other conditions. Some have died from gorging until their stomachs actually burst.
