I have had all sorts of pain - back, shoulder etc (attribute to TMS) that led to an obsession with what I eat.
I grew up in a vegetarian family where I have seen 90 year olds thriving on a simple starch based diet eating copious amounts of dairy. I cut out gluten, dairy, sugar etc. I even saw an abatement of symptoms as I continued on this diet. I tried all sorts of diets feeling better on some than the others. I checked my B12, calcium, magnesium levels obsessively. I took a magnesium supplement. Then fretted that it might cause calcium deficiency. The chain continued. The breaking point came when I (the supposedly fit diet conscious individual) went on a trip with my 80 year old uncle. At the end of the long walks and bumpy car rides we reached out destination. My uncle asked me if I needed anything for my back pain. He was fine of course and would buy me the meds while I rested. My cousin (his son) was right next to me moaning about his IBS and how his shoulder pain was acting up since he had left his theraband at home (I kid you not). He declared that without his daily external rotations his life would be hell. Then we got into a rant about the spring beds in both our rooms that for sure would have shellshocked my uncle. Needless to say, he drove the entire way back. Of course, my cousin and I reclined in varying postures on the back seat complaining about bad roads and the car's suspension.
My personal theory is that this is TMS. We have too much information on all these in the media and the brain probably uses that to create the symptoms. I suspect this to be the issue (at least in my case) since I have virtually never had those symptoms growing up. I feel that the brain needs an excuse to distract. When we are obsessed with our diet we are distracted from the feelings of repressed rage. Obsession with the diet is distraction enough.
I started looking at the people I came across. I began to see those friends and family who did not care for their diet, who were not the sensitive type (for lack of a better word) tended to thrive on any diet. Across the board, fat or thin, muscular or obese they were immune to
chronic pain. These were the people who did not give much thought to how the world perceived them. They were usually pain free. Irrespective of whether they were vegetarians or meat eaters. The important thing was that they were comfortable in their own skin. Again, I am not commenting on whether they had other diseases later on but just the fact that they were usually happy and pain free. The way I think now - getting sixty to seventy years of pain free living eating whatever you want to is a blessing in itself

. Look around you and let me know if your observations match mine.
I don't eat junk food anymore but I am trying not to obsess over the food I eat. I have got gluten back into my diet. This might have caused some of the pain symptoms to come back but I will handle that as TMS as well. I understand these observations do not qualify as scientific evidence but so is looking at a youtube video of a few fit individuals and coming to conclusions based on that. There might be huge scientific literature backing up each diet but as we know the TMS brain is a beast capable of giving us anything as a symptom. I hope this helps you in some small way. Peace.