I found I can't just decide never again to eat the things I like and never again feel sated. Feeling hungry constantly isn't exactly my idea for the rest of my life.
Alternate day fasting lets me survive a day with no calories knowing that the next day I can be sated and eat (almost) whatever I want.
I have also found that when I eat every other day I put much more attention to what I eat on those days -- I mean, if I just did not eat yesterday and I won't eat tomorrow I want to eat well today. Even if I am going to eat sweets -- I will try to go for something better and not feed myself with garbage.
I also found that alternate day fasting is good willpower training. Being able to restrict myself from eating for an entire day somehow trains me to be better at other things that require willpower.
When not eating I would not eat or drink anything that has any calories in it. I typically drink water, black coffee or green tea.
I have also tried longer fasts from time to time (2-7 days typically, 2 weeks once) and then I would supplement with vitamins, l-tryptophan and lean broth/bone broth in moderate quantities (a cup a day), just for safety and general well-being (l-tryptophan is precursor to serotonin and mildly anti-depressant).
Intermittent fasting is hard at the beginning but after about 2 weeks I get used to new regime. It seems it is the same every time I start it anew. It might be getting easier but I think that's because I already know what to expect.
Also, when intermittent fasting it is much easier to start longer fast. I find, when fasting for more than 2 days first two days to be the hardest.
What I've discovered doing 72 hour fasts is that what I eat when I refeed matters a lot less than when I'm eating throughout the day. Keto made a big difference in my initial weight loss journey, but I find it to be somewhat miserable for maintenance. Yet, with fasting at least 48 hours, I discovered that the macro composition matters a lot less in relation to ketosis. In my eating window, I can eat rice, fruit, etc., and it will knock me out of ketosis for a short while but I'll usually be right back in ketosis between 24 and 48 hours from then. I feel much better in general getting a small amount of calories in, and it hasn't significantly effected my weight loss. In fact, when I was sick a few weeks ago, I stopped fasting and basically ate berries all week. The following week, I went back into a 72 hour fasting routine and still managed to lose a few pounds from where I was at before I got sick.
Put simply, I think the longer a fast is, the less that the need for keto matters. Keto combined with IF can work for a lot of people, and in a lot of ways they are complimentary in their benefits, but people can also tip the balance in favor of either more keto or more fasting and find their own combination that achieves their goals.
The best I've ever felt was keto, the easiest for me to adhere to was calorie tracking. It's marginally harder if you eat out a lot, but if you cook for yourself and can throw everything on a food scale for a week or so until you get an idea of what's servings of your most commonly-eaten foods looks like, tracking calories made losing weight for me and reducing my daily eating almost comically easy. There's a switch in my brain somewhere that works really well when I have to enter the calories of everything that goes in my mouth into an app....suddenly that cookie or those chips that were so hard to resist aren't a thing for me at all....my brain manages to yell "200 calories for THAT?? Nope." I found myself eating more at the end of the day just to hit my total calories and macros.