I would like to know too. But I can tell you about my experience.
I experienced something similar after moving to college from my hometown. Obviously the food was much different to what I had at my home. This led to me having cognitive and physical issues for 5 years that I stayed in the dorms. I used to feel like a zombie, no motivation or enthusiasm and a host of other symptoms. During my internship in my final year, I was diagnosed with something similar to IBS.
The solution was just to be conscious about what you eat and how it makes you feel.
The food at my internship was of such poor quality that it made me feel drained for many hours after eating. This was what prompted me to get checked seriously.
Am I better now? On average yes, but never like I was before moving to college. I eat a very restrictive diet. Semi permanent damages to one's system is not uncommon for people diagnosed with IBS.
Sure, it was iron overload [1]. I thought I could "eat like an adult" there and catch up on leafy greens which I always hated. But it turns out I hated them because my body can't process out iron. It kinda turned on its head my idea of "trying to be healthy" which is why I didn't mention the specific thing.
All of my side projects from the time are extremely uninspired.