There is a bit more to thyroid function than just TSH however. For some reason, some people can have normal TSH, but still be hypothyroid. I am one of them. For some reason, I can not convert T4 to T3, so taking a T4 drug (synthroid, unithroid, levothroid, etc.) can make my TSH 'normal', but not do a thing for symptoms. I also take a T3 compounded drug, and that helps a lot. I don't lose easily though. If your doctor checks the whole thyroid panel, and everything looks normal, you may have other metabolic problems that can inhibit weight loss, such as insulin resistance. You might want to ask about having your insulin levels checked, especially if you carry weight around the middle, and tend to be hungry a lot, and crave carbs something fierce.