I got sick a few weeks back and couldn't eat. I had all I could do just to gag down a glass of juice. I was consuming little to no calories on a daily basis for what seemed to be about a week.
The results? I was around 170 lbs at the start, hit a dehydrated 155 lbs part way through it before I started drinking gatorade, and now that I'm better and eating my top weight is around 165 lbs. So I lost a good 5 lbs of fat, lost an inch off my waist, and my belly is now flat.
From my experience I am convinced that fasting works phenomenally well at dropping the fat, and our bodies are meant to do it if we have to. But also, it's good to have a few extra lbs of fat on your body in case you need it like I did. I'm just talking maybe 5 extra lbs, so for a guy for example, it'd be better to be say 6% body fat instead of 3%.
Also, for guys, you'll probably have to be a lot lighter than you think if you want to see your abs. For me for example, I've been lifting my entire life and I'm thinking I probably still have to lose another 5 lbs of fat if I want to see my abs more clearly.
Mind you I'm not lifting as hard as I was back when I was competing in strength sports, but even if I was I just don't think I'd be weighing that much more. Maybe 5 more lbs if I was working brutally hard, and lucky.