Whereas normally the body will break down carbohydrates as fuel, a ketogenic diet supplies calories mostly in the form of fat and hence the body must switch gears and break down fat for fuel instead, a state known as ketosis. This is also what the body does when fasting.
It's not known exactly how ketosis hinders seizures, Thiele says, but the impact a ketonic state has on cell production is currently under investigation for a number of diseases, including Parkinson's and Alzheimer's, and certain types of cancer.
Cancer cells grow rapidly and use a lot of energy, and the ketogenic diet basically shuts down the cell's energy production, thereby potentially slowly the progress of the cancer, Thiele says.
Luckily for Jack, he won't have to give up ice cream and cookies and other favorites forever: Kids can often be eased off the diet after two years.
"World News" spoke with Evan Kristal, 14, who is considered another "miracle" case when it comes to the ketogenic diet. When Evan's parents came to Mass General's Epilepsy Center years ago, "they were pretty much in a place of desperation," Thiele says. Evan was having 40 to 50 seizures a day. Within weeks of going on the diet, he was down to zero seizures a day. Two years later, Evan went off the diet, and began to eat like a normal kid again, and remained seizure free.