Can weight fluctuate during 6mth diet?

[Bunnyrae 3]

This may or may not be a stupid question but during my 6mth pre op diet can my weight fluctuate? I weighed 272 at my initial visit I'm 5'8" that puts my BMI at 41.3 today was my 2nd mth visit I've gained 11lbs! They have me so stressed about not going under a 40 BMI that I'm gaining weight like crazy. So Dr is saying just don't go under the 40 BMI which will put my weight right at 263, so it's ok to go up and down right? But I should weigh less than my initial visit?

[MrsB2007 90]

Some people's weight does go up and down a lot.. mine went up like 6lbs. But I would double check with the surgeon to see if it is ok. . Some insurance will deny if there is any gain at any point, and some will deny if there is a gain at the end of the diet.

[nerkerle 18]

My BMI was 40.8 at first visit with surgeon's office. During the 6 months, I lost about 20 lbs which put me under BMI. The insurance company used my starting BMI and I got approved in 4 days. Anthem BCBS. Date 05/06/2015.