AAAAARRRRGH! ;-D That feels better!
Read ANY list of "symptoms" for ANY deficiency/toxicity/signs-you-have-a-problem, and guess what is usually #1? Right the first time!
Fatigue is a symptom of too little exercise ... or too much. Fatigue shows up when you're not absorbing enough iron ... and when you have "iron overload." Fatigue means you're not getting enough B12 ... I mean carbohydrates! ... it means you're hypothyroid ... uh -- it means you're getting too much protein! or ... not enough ... or ... ummmm....
[sigh] Fatigue means your body is not happy, but exactly what your body isn't happy ABOUT is not actually being told. There's a good chance that your thyroid DOES have something to do with it, but that's because it's the mechanism through which your body is down-shifted -- because an unhappy body wants to take it easy, husband its resources, and get better. It doesn't necessarily mean that there's anything actually wrong with thyroid function -- it's doing what it was designed to do.
Fatigue can mean almost anything. Don't let ANYBODY tell you that, because you're fatigued, you should subscribe to THEIR specific protocol.