Ah, the old Medical Student's Disease. It's possible that when people that are new to paleo read about all of the Neolithic diseases, they think to themselves, "I show symptoms of these!" or "I want to avoid this."
But that's a completely different thing than hypochondria. Certainly removing just wheat, as Dr. Davis shows in Wheat Belly makes a huge difference, and improves health to the point of being noticeable.
In my own case, I'm a geek. I prefer to learn about something deeply and so I dig up as much information about everything I can, whether or not it personally affects me, because it's interesting, not because I suffer from this or that. I could see how someone who knows me well might claim something like orthorexia, but even that's false, as I do eat some CAFO meats, for example, based on the risk level. (i.e. I'll happily consume lean CAFO beef, but I'll avoid CAFO eggs, chicken, farmed fish.)
But even Orthorexia* is a made up disease, and it's not even recognized by the medical establishment. If I were paranoid, I'd say it was an astroturf campaign by the crap-in-a-box peddlers to lessen the impact of the loss of sales of their products, by negatively labeling anyone who wishes to be healthy.
But hypochondria is an actual mental disease, in the same way as full blown depression is not "My dog kicked the bucket and my wife ran off with my best friend, and my pick up truck has four flat tires."
So I'm more inclined to say that people who come here looking for answers are doing just that. Some of them may have been diagnosed with an issue, others could not find an answer, for example, they might have a sensitivity to gluten, but the commercial tests, that only look for one out of the 16 (or whatever the number is) of gluten antibodies, and show all the symptoms and improvement when eliminating wheat, but show negative on the test, are no longer trusting of the mystique of the white coats and authority of the medical system that has failed them.
I myself was never diagnosed with a wheat sensitivity, but, I can tell from the changes I experienced, some of which may well be placebo effects, that I no longer feel pain in my joints, despite having had severe damage to both my knees, I no longer have brain fog, no longer have weekly headaches, lost a lot of fat, lost the nightly GERD, and when confronted by a tall staircase, I now experience the urge to run up it, 2 steps at a time, when I previously would cowardly choose the escalator instead, and I've also developed an immunity to cold. So n=1 and all that. :)
Certainly, you could say that the one time this year I accidentally exposed myself to wheat, and experienced headaches, diarrhea, shivering, and a sensitivity to cold, that the particular episode might have been an nocebo effect. Sure, I suppose some of those symptoms could have been in my head, but I personally doubt it. :)
I find myself saying, "we are all n=1 experiments," and this is true in the sense that we're experimenting on ourselves and it's not a double blind experiment, so we can easily skew the results to placebo/nocebo by knowing what we are testing for, and expecting what the results should be. But in the end, we are discovering what works for us.
We are here because we were damaged by our old Standard American (replace with wherever you live on this planet) Diet, but because of our environment and our genes, we were damaged in slightly different ways, so what works for everyone might not work for us specifically. That doesn't mean it's all in our heads, just because there are differences.
Some of us do better on higher carb, some on starches, some on fruit, some at VLC or ZC. Some do better with certain exercises, some do better avoiding dairy, others embracing it, some have problems with nightshades or eggs. Some of us can even tolerate some grains. For example, Robb Wolf can eat corn tortillas occasionally, where others would have severe reactions.
But all of us here follow something we call paleo, or primal, or whatever other word the authors of the book we've read decided to call it so as to carve out a separate niche for themselves.
And yet, we can share our experiences and possibly help others with the same kinds of n=1 issues. My n=1 issues may not match yours, but if they do, I'm happy to share what I know that worked for me. Maybe it'll work for you as well. Then again, it might not. So you'd have to experiment and become an n=1 yourself.
And hopefully, you'll return the favor to the new folks that show up here looking for help, and are suffering from the things you've got knowledge about.
*Edit: Here's what Wikipedia has to say on Orthorexia, for those who haven't looked it up:
Orthorexia nervosa (also known as
orthorexia) is a term used by Steven
Bratman to describe people who have
developed a fixation with healthy or
righteous eating and has been
referred to as a mental disorder.
It is not a medically recognized
term. Bratman claims that in rare
cases, this focus may turn into a
fixation so extreme that it can lead
to severe malnutrition or even death.
Here are the so called symptoms of Orthorexia.. If you're eating paleo you'd trigger 2-3 of these right off the bat, possibly more, marking you with a mild case of orthorexia.