It's a really controversial subject and I have to watch what I say for fear of upsetting certain people, but I wonder if what actually happens is that a sufferer starts off with an illness that knocks the stuffing out of them and has them laid up in bed for several months.
After that, they are actually on the mend but are very weak from the after-effects of the illness and from lack of exercise. When they finally do try and get out of bed they feel really exhausted, think they are still ill and go back to bed to recover. Of course, that makes things worse and the weakness deepens...
When I was 9, one of my classmates became seriously ill. I can't remember what was wrong with him but he disappeared for a year. I was told that he was in hospital but I didn't see him again until 12 months later. When he finally came back to school, he looked awful. In those days, I don't think there was the same emphasis on physiotherapy, and getting patients out of bed whenever possible. He had basically been left to wither away for a year. His legs looked more like the size of my arms and he was on crutches and was having to learn to walk again. It took him the best part of a year of struggle to build his strength back up. It would have been very simple for someone to persuade him that he was still ill, and to send him back to bed.
Having said that, I've had some sort of bug 3 or 4 times in the past 20 years which left me feeling exhausted, without otherwise making me really ill. I had it once as a student. I got back from university one evening and was so tired that I laid down on my bed as soon as I got in and slept for 14 hours. I normally sleep for 6 or 7. For a few weeks, it was all I could do to walk slowly and read a few books. Perhaps ME sufferers have something like that but for some reason never recover from it? The only thing is - if so, why can't doctors detect the virus (if it is a virus) responsible?
You can understand why people who feel absolutely wretched (or who have loved ones who do) don't like being told that they might not actually have a physical illness, and that it could be all psychological!
I'm convinced that the vast majority of ME sufferers genuinely are physically very weak, but I wonder how many of them could regain their strength if they worked with very skilled physiotherapists and nutritionists to build their strength back up again?