Interesting thread! Love reading about others' experiences.
I went keto about a year ago. Wasn't doing well physically... way overweight, headed towards diabetes with likelihood of heart attack and/or stroke looming pretty big. Wasn't good. Had to make a change. (Basically came from a vegan/vegetarian background. Yeah, I know, it's not supposed to be that way according to many, but it was for me.) Over the last year, I've dropped about 70 pounds and am doing a lot better in most every way. I do "lazy keto", which means I don't track every morsel of food and drink. I eat a large variety of foods including beef, poultry, fish, dairy, eggs, non-starchy veggies, and small fruits. I do not go hungry and I eat desserts just about every day (homemade, keto-friendly).
There are a lot of variations in eating that take on the "keto" name, all the way from never touching a vegetable (carnivore) to never touch an animal product (vegan). Though I can't and won't try to do either of those, I do fall in the middle and now consider myself a healthy omnivore. I try very hard to eat good quality food (local and/or organic and/or home raised when I can) regardless of whether it's meat, eggs, dairy, veggies or fruit since there are some pretty awful things being sold in the grocery stores these days in all of those categories.
To the subject at hand, I don't do a lot of fasting. I do occasionally, but it's not anything regular and it's mostly not planned. It wasn't long after my wife and I started eating keto that we got away from eating three meals a day, just didn't want three meals. We've pretty much gravitated to two meals a day as our normal eating, breakfast and then supper. We don't snack. We don't feel any need to. But when we eat a meal, we generally eat very well. We don't leave the table hungry at all.
On some occasions, we will have something going on, could be numerous things, when we'll either be busy or making a meal isn't convenient, when we'll just skip it completely. As I said, it's often not planned. But that's completely OK. So when that happens, it turns into a 24 or maybe 36 hour fast. No big deal, really. It's a non-issue and almost unnoticed.
Before we went keto, skipping a meal would have been a very big deal. Our bodies were really not able to handle running out of fuel (carbs/sugar) and the 4-hour hunger monster was a very real thing. After eating keto for a few months, our bodies become much more accustomed to burning fat. And the thing about that is, our bodies have a ready supply of fuel onboard. No problem. I rather like that. The 4-hour hunger monster is gone.
Traveling became easier. We always used to HAVE to have snacks, sugary drinks, caffeinated drinks, plus we'd have to stop at least twice for a meal. Not anymore. Mostly, we have some water with us and maybe a few nuts just in case someone does get a little snacky. We've learned that the nuts often go unopened. We are just fine not eating.
(FWIW, I usually feel worse when I snack than when I just don't eat. If I eat a little, I want a big meal. If I eat nothing, I'm pretty contented. Grazing just doesn't fit well with me anymore.)
When I first started keto, I wasn't a big Jason Fung fan. But he's kinda grown on me to the point where I really like the guy. He seems to make a lot of sense in what he says. I haven't read his books but I have watched his YouTube presentations which are excellent.
A person doesn't have to go keto to do intermittent fasting. But I think it probably makes it a lot easier to do without undue hunger and stress. Fuel source onboard.
Sorry to ramble on... You hit on a topic that hits home.
BTW, I have about another 20 pounds or so of weight to lose. It came off very quickly in the beginning but the rate of loss has slowed to a crawl, which is exactly like I wanted it. I sort of have this picture of an airplane coming in for a smooth landing, touching down softly such that you hardly notice. It may take me another year to get rid of that last 20 pounds and I'm perfectly fine with that. It's like I'm at about 600 feet in a very slow descent right now. I like how it's going. I like how I feel. And this way, it's not a big deal about when I get there, how am I going to adjust to eating to maintain. Nope. I basically just keep on keeping on. And considering I like what I eat and how often I eat, it's really, really easy to just keep on keeping on.