I hate when people tie it all up so simply to CICO. MAYBE at the base Kcal level it is true; but in the psychology of what drives people to eat beyond just "eating to live", it's not helpful. For one thing, counting calories -- along with accounting for calories burned due to exercise -- is soul killing (and you can't out-exercise a bad diet), so I find that useless to know.
I needed something that was going to teach me about MY eating habits and, more importantly, get beyond my inability to control my eating by willpower. I don't have an eating disorder; but when I fast, I realize how much of eating is boredom or distraction or just the "action" of eating. That was quite a revelation to me as I did not consider myself an emotional eater. I still don't "eat my feelings" but I didn't think I was engaging in a "habit" of eating, if that makes sense.
I am not fasting right now per se (more like OMAD); but because I'm focusing on being more mindful about using willpower to curb my sweets habit, I have lost 6 pounds in 2 weeks. I've also learned to add ACV to my daily water consumption and have made it a habit and I'm so proud of myself!
Fasting isn't for everyone, I'm sure. But for me, it's been a beneficial tool that, because I had never fasted before, gave me a lot of insight to my own psychology of eating and further cemented my mantra of "hunger is not an emergency".