I did try a diet like this in 2006. It made a big difference to my energy levels and got rid of my cognitive fatigue. However, it was awful.
The amount of kale/greens that you have to eat is enormous and each meal takes hours to prepare and eat. At that time, ‘green smoothies’ were being touted as a cure-all to most conditions, but you need a very powerful blender to chew up kale and celery.
I ended up buying a Waring blender on ebay.com and it was sent from the US - it was a lot cheaper than the £400+ that it costs in europe, but the smoothies were disgusting. Blended cabbage is not nice. It’s just about bearable with apple and celery and spinach instead of cabbage/kale.
If I was to find myself feeling that ill again, I’d probably try it once more. You have to be feeling very bad to go this route. Fortunately (touch wood, knock 3 times etc) I haven’t been as ill as that since then. So maybe it works - but you will need a very high powered blender, a Champion Juicer (not cheap either) and a lot of patience. Still, you won’t suffer constipation!
We used to eat a large salad for lunch, with sunflower seeds and nuts and chopped raw spinach leaves and sometimes raw salmon. The biggest change is in your shopping - nuts and seeds become the mainstay of your diet and it’s easy to run out of them.
If anyone wants more info on this type of diet, I’ll happily help. It’s not a cure. I still inject Rebif and take amitriptyline for nerve pain and 4 hypertension drugs and thyroxine. It did help me a lot.