I think every doctor is different, but mine does it that way. If I could've dropped more in the 6 month program (for insurance approval), I may have been able to drop back to 2 weeks. The Holidays made that really difficult though!! It gives more time to lose additional weight prior to surgery. It also reduces the amount of fat on the liver (which reduces its size). Generally, the higher the BMI, the higher the fat in and around the liver. The reduced size of the liver makes the procedure alot easier for the surgeon. Hope that helps.