I know what caused my cfs. When(/since) I was little (age 4 or 5) I had an aversion to most foods before I ate them, I sensed that the foods available were not quite right. All I would feel like eating just about was raw salad, mangoes, pineapple and I had to be encouraged to eat other stuff and after a while I got accustomed to the foods available and just ate them despite my sense not to.. About 3 years ago I realised when I was eating asparagus that it was having a beneficial effect on my circulation and that I could sense how foods would effect my circulation before I ate them (and remembered about how I'd had this sense since I was little). I followed that sense and found other foods also had a slight beneficial effect on my circulation: spinach, cabbage, kale, passion fruit flesh (not seeds), tomato flesh (not skin, not seeds). Following that sense I also realised African meats and fish and grains and beans were near enough neutral to my circulation: camel, ostrich, ostrich egg, springbok, zebra, cape snoek, cape hake, teff, kilombero rice, black-eyed beans. (and salad and emmer generally neutral also). Meanwhile the rest of foods(/ingested substances) effected my circulation negatively, the worst being unnatural substances (such as an antidepressant). Thus I realized I had(/have) a progressing (according to my diet) circulation condition over time explaining the gradual onset of coldening extremities, pins+needles more and more frequently, during my teens feeling unhealthy and then the puzzling lessening vitality, and later fatigue+joint pain. Eating a diet of African origin foods and neutral foods and beneficial foods, I can stop the circulation condition from progressing and even marginally improve it. However this is nearly sustainably implausible as it's very difficult to get enough energy in doing this (as living in the UK where limited neutral+benefitting foods available). My theory is that humans evolved mostly in Africa, specifically to the African environment, and some people, such as I, have a neutral circulation reaction to African foods and generally speaking (besides leafy greens and tomato flesh and passion fruit flesh and salad) have a negative circulation reaction to a diet outside of that (including swallowing substances outside of Africa), leading to a slow progressing condition (fatigue, pins and needles, pain in joints, etc) depending on diet and ingested substances. The sense is an intuitive sense of how something will effect circulation pressure or viscosity or speed or something along those lines.