Basically when I was younger, around 15 or so I went onto a diet to lose weight (I was around 15 stone, and I'm only 5ft 8). I lost around 5-6 stone over 2 years, and I got down to around 9st 3lbs. I was able to put weight on to and I have sat around 9st 10lbs for around 3-4 years and I can't seem to put any weight on at all, no matter what I eat, nothing, I just stay at 9st 10lbs. I am wondering if I am suffering from a hyperactive thyroid, I have never spoken to the doctor about this because it's not really an issue I'm just wondering what could be the reason behind this. I have been looking at the symptoms of hyperthyroidism and I believe that I have the majority of the symptoms, such as anxiety/irritableness, mood swings, difficulty sleeping etc. Would it be worth getting tested for hyperthyroidism?