Hello! I just saw this post and wanted to say that I am also on Effexor, along with other meds that make me weight loss resistant. I recently got blood work done because of the meds, and my thyroid levels came back low. At my pleading, my doctor put me on the smallest dose of thyroid medication there is, but it has already helped me to not be so weight loss resistant. I, too, have been knocking myself out to lose weight and couldn't lose A POUND. It is sooooooooo frustrating and ~ yes ~ depressing. But, in the past two months, I have lost 9 pounds, and I think it is because my thyroid levels have balanced out. I am not saying that this is the case with you, but it might be worth having your thyroid levels checked if this EXTREME weight loss resistance continues despite prolonged SERIOUS attempts to lose weight. Best of luck to you!