The goal is to starve the pancreas, however, if your BMI is low to begin with in Insured surgery, this can also disqualify you. If you are doing Medical Tourism, BMI guidelines and prep are typically 2 wks for BMI 40-55, LOWER than that is only couple days clear liquid only. 55plus, extended diet based on health, is mapped out. The first 4days suck. Expect Migraines, nausea, vomiting & extra female cycles. To ease the symptoms Ginger & Pineapple tea, (nausea) freeze and put in Dixie cups for shots after too, Sauna for migraines, 15 min a day 2times is the same calories burned as a 2.5 mile walk, and female supplies as it can happen day of due to stress.