I think it depends on the hospital, I'm diabetic and Luton put me on it for 4 weeks, I had to lose 5% of my bodyweight during that period, there is an extension of up to nine weeks in total, this was just to prove that I was serious and prepared to work at it before they would grant surgery. When I go back for my pre-op at the end of Jan I expect to be put back on this before the actual surgery in Feb. At the time of using the milk diet I was told to lower my insulin 100>50 units, during the four week period I found I had to drop it again by 10 units down to 40, (Lantus), but I had no ill effects during this period if anything I felt better for it.