Seriously.. 30lbs!

With a day-of-surgery weight of 286, the doc said that I would lose 25 pounds by the time I saw him a month later.  I lost 24.  In the third month, my weight loss was 12 pounds.  Probably would have been a couple more pounds if I had been religious about exercising, and I'm trying to get back into that habit.

The weight loss slows down as your body weight reduces and as you tend to add a few more calories as you become comfortable with your pouch and it expands a little.

How much you have to lose is another factor to consider.

4months-2days ago I went in to surgery at 322, after having lost 55 in the 18 weeks prior to surgery. by the time I'm 18weeks post-op, I should be down another 100+

I'm at bout 90 lost and averaging just over 5pounds a week. That's averaged out, I've had 3-4 stalls of 5-8 days, so some weeks have been over a pound a day.

My BMI was 53ish at my heaviest last year, I'm closer to 30 no... if you were at the border for surgery at about 40... you likely won't lose as fast.

but again, YMMV.

My BMI is 49 right now at 365lbs.

in comparision to your case, there will be no way I shed 55lbs pre-op.  I'm expecting a date of surgery weight around 350 given the pre-op diet.  So the vast majority of weight lose I will experience will be post-op.

Given what I read and the other posts to this question, it sounds like 20-40lbs a month for the first 3-6 months "seems" expected (obviously eating the correct foods and exercise will help ensure this).