I haven't done any fasting longer than 18 hours, purely because I didn't need to last time. The reason I loved the keto way of life last time was that I found it easy, I didn't feel hungry, I could eat things that are banned on most diets (mayo, cheese etc) - I can forgo chocolate and sweets, but not cheese!) and I felt better and slept better. I just don't know why I can't get into it and stay there.
I'm eating less than 20g carbs a day and logging everything. Mainly salmon, avocado, eggs, cheese, macadamia nuts, chicken, coconut milk and some salad.
I'm not a massive carb fan in general, not bothered about potatoes or rice and am gluten intolerant so avoid bread, pasta, cakes, biscuits etc as I don't like the GF substitutes. My main carby cravings are fruit, sweets and chocolate - all of which I'm obviously avoiding now!