What happens if you don't eat much for 4-5 years?

Been dealing with chronic illness recently, much worse than before. I barely get to eat much every day, for the past 4-5 years. Had infections that worsened my baseline, but currently dealing with cci, tmjd, horrible posture, horrible fatigue, sleep apnea type symptoms, and pots like symptoms. I'm in constant fight or flight, and my brain can no longer think anymore. There was a period where I was eating very well for 3 months but no improvement, and my reactive hypoglycemia hated me for it. Now what do I do? I guess I'm just ruined.