No, you don't have to purchase food, it is all in what you eat. Cutting out sugar and simple (vs. complex) carbs, eating bulk low glycemic index foods mostly. My daughter bought one of their cook books a while back and I started looking at it and the food recipes looked good and pretty easy.
Most of the information is on line so you really don't have to buy and books.
Height: 6 ft. 6 in.
Starting Weight: 250 pounds (8-07-2010)
Current Weight: 246 pounds (8-10-2010)
Goal: 215 pounds (12-31-10)