I have tried a few different intermittent fasting protocols - 4/3, 5/2 and currently the 16/8 Leangains style that
@Somnambulist is referring to.
I found the 5/2 (i.e. 2 "fasting," sub-500Kcal days, every week and normal eating on other days) and (even more so) the 4/3 made me lose fat very rapidly a few years back, but I'm liking the Leangains 16/8 a lot better for leaning out whilst getting my newbie lifting gains now I'm working out again.
My reading on this tallies with
@Somnambulist's point above - the jury is out as to how much of the weight-loss is down to the 16-hour fasting period itself and how much down to calorie control (and having an eight-hour eating window basically just meaning you eat less...).
Even with fasting hours, you still have to be careful of calories - ideally you'll want to watch your macros pretty carefully too.
My own diet is based on training every other day, and eating at maintenance calories or just under on training days and about 600Kcal under maintenance on rest days. For me this is 2000Kcal one day, 1400Kcal the next. BUT I also make sure to get at least 160g of protein every day to help to spare muscle while I lose fat. I think this is quite important since you don't want to lose muscle whilst dieting.
As
@booyaka says, too, though - if you eat a bit below maintenance calories and eat clean you'll lose weight regardless.
Personally, I've found my best results for rapid weight loss were with the 4/3 diet, though it did get pretty demanding and gruelling pretty fast and I'm sure I burned off a fair bit of muscle doing that so I'm in no rush to go down that route again. I've been exceptionally pleased with my results since doing this 16/8 diet for seven weeks now - but as I say, I am sceptical as to how much this is down to any fat-burning associated with the fasting period itself.
If you want to lose fat, preserve muscle and increase strength, I think the main consensus is that it can help to be zig-zagging calories (i.e. eat at or near maintenance every so often, and about 400-600Kcal below on other days) and you want to be keeping protein intake consistently high (around 1g per lb of bodyweight is recommended). Also make sure you're still getting enough healthy fats and plenty of water. You can add a fasting period on top of that, but I think those are the key foundations.
I personally like to use 10g BCAAs and 5g HMB (and a large, strong coffee...) 20 minutes or so prior to my fasted 6am workouts. I'm not convinced there's anything magical about this and it might even be completely pointless, but it does help me feel I'm getting fuel to my muscles with minimal calories at a time when I really don't want to have my first meal, and then I can pick up my usual workout-day diet post-workout without having to re-calculate my calorie or macro goals.
EDIT: re your last question about post-workout evening shakes... as has been said, it's not worth stressing about keeping to a strict 8-hour eating window so long as your overall calories and macros are in line. I recall reading a number of recommendations to get some quality protein in you after a workout and some people argue for including some carbs to replenish glycogen as well I think. A protein shake should be okay. Cottage cheese is another staple evening protein source as (IIRC) it's primarily comprised of a slower-digesting protein - and it's easily snackable straight out the pot too if you want and it also mixes well with fruit. Just take off the 150-200Kcals or so in whatever you have from your food intake earlier in the day.
