FWIW I went through severe fatigue starting the end of May through early July. 2 visits to the doctor, bloodwork, thyroid ultrasound, EKG, etc. and nothing was found. I simply could not get out of bed in the morning. I would lie in bed and my legs would feel like they were weights. I would drink a bunch of coffee, get a boost of energy in the afternoon/early evening and then collapse again. I did not have any pain or aches, thankfully, so sleeping was easy for me. Also I did not have weight gain either. My running ended up coming to a standstill at that time and I have not been able to get back on track since unfortunately.
I did look into adrenal fatigue but like SG says there is no medical backup for it. I did follow the recommendations from a few web-sites which are pretty generic and useful for anyone - get lots of sleep, eat well, relax and give your body time to rest up. No short cuts, medications or miracle solutions.
No I do not think that people around me took it seriously but what can ya do? Raven was supportive even if he did not quite believe I was going through anything more than tiredness - at least at first. I did eventually take a week off work and scheduled doctor's appts that week. With holidays/vacation, plant shutdowns and a professional conference, I ended up with 2 weeks at a client's site that I regret being there. I know I did not give my best effort those weeks. But I did not realize quite what I was dealing with either.
I know my general practice doctor is great but he was stumped and truthfully at the end I had a feeling that he just did not quite believe me since he could not find anything wrong. However when I mentioned having some fuzziness with my thinking from my fatigue he was more than willing to prescribe some medication for me. I turned it down! I do find it strange and bothersome that a doctor is so willing to prescribe medication for a symptom when they do not know the root cause.
So yes I do appreciate what modern medicine has gotten us (good sanitation was equally as helpful) and I do believe there are many quacks out there, however in between I think there are some interesting alternatives that are definitely worthwhile to consider cautiously. I think some of the medical profession closes itself off at times. Dr. Weil is one of my favorites because while he is interested in alternative medicine, he is still very traditional at his core.
My 2 cents.
But what is happiness except the simple harmony between a man and the life he leads? ~Albert Camus