Are you taking generic or name brand drug? I sure understand your frustration. I had fluctuating weigh loss and gain when I was on generic some years ago. I did some research on my own and found out that others taking generic had experienced this same thing. I went back to my doctor and requested a new prescription that stated "name brand" only Synthroid. This helped stabilize my weight issues a lot. My numbers do change once in awhile and so the amount of Synthroid I take has to be adjusted accordingly, and this of course might cause slight weight gain or loss, depending on whether you are getting the correct amount of medication.