I do water fasting. My longest fast was 20 days so far. The first two days are the hardest then the ghrelin drops right off and it’s plain sailing from there.
Personally I have issues with low blood pressure, which manifests as weakness, faintness and lights behind the eyes. This is easily fixed my taking salt tablets and sports electrolytes. I like Rehydr8 that doesn’t contain sugars like a lot of the sports drinks and chewables do.
I’ve tried green tea fasting and found it harder - somehow the green tea maintained some appetite, and caused food cravings. Plain water is easiest for me. Also several days is easier than 1 or two at a time, because the first 2 days are the hardest so why repeat them over and over?
Benefits - mental clarity, more time, autophagy, metabolic reset, reduction in allergy symptoms after fast ended, clearer skin, healing of scars, easier meditations and better clairsenses, better flowing qi.