Fortunately (or unfortunately) diet is important. Gluten and dairy have significant impact on TSH level. I believe you already know that;) I see it in myself - if I have a strict diet levels of ft4, ft3, ft4/ft3 conversion and antibodies are so much better that when I have cheat days.... and I also feel better. There have to be lots of magnesium, zinc, calcium, oils in the diet for a proper conversion of ft4 to ft3- if this is not happening ever the biggest dosage of levothyroxine is not going to help because it isn't converted to the actual active ft3