Think you have some things confused here. Clen has nothing to do with T3 which is a thyroid hormone. Over time, clen will become less effective. There is a down regulation. I see that the popular way to run clen by all the bros online is some variation of 2 wks on, 2 off. Or some other on/off/on plan. The idea taking benadryl is to keep your body sensitive to the clen. This does not work. Keto may work to an extent, but personally, I have never used it. I avoid down regulation by using it for 2 wks at the lowest dose that will produce results, then increasing by 20mcg and repeating this process of 12-16 wks. It works great for me and the people I have helped. So you can run it 2 on, 2 off if you iike. It will work that way too. There is more than one way to do things. I just prefer my method and have never once not been lean enough