I've been on synthroid since I was 12 (now 22), I never noticed weight loss when I first started with it, and it definetly didn't stop me from gaining when I when to college and basically ate whatever I wanted for 3 years. However, since starting a low carb diet, I don't seem to be having any more trouble losing weight than "normal" people. I still feel sluggish but I don't really know how I should be feeling, I have nothing to compare it to.

Before seeing this forum, I didn't even really know about T3 vs. T4, all I knew was that I'd taken a pill every day for the past 10 years. Next time I get bloodwork, I will be sure to ask the doc to check my T3 levels and test for PCOS.

I wanted to thank everyone for all the great info here, its amazing what I didn't know before!