I have BCBS Fed and I was just approved for the surgery. It doesnt matter if you gain or lose during the 3 month supervised weightloss plan as long as you stay within the BMI of 35. I was actually underweight during my first appt. and I gained for the next 2 weightloss visits.There is no rule against gaining or losing as for now, however other insurance plans do require you not to lose or gain. Hope this helps and good luck