My proven way to lose fat and keep muscle is to eat 5 or 6 small, balanced meals a day, with most of the protein in the morning to early afternoon. NO fats or carbs after about 4PM. Everybody is different, but I can be really pudgy, or really ripped. About the fasting, I've been in some hard times in the past, and only ate once or twice a day for awhile while I was in my late teens/early 20s. At one time, I discovered I was down to 129 lbs, at 6 feet! Friends said I looked like a Nazi prison camp escapee. But I still had a thick layer of FAT. By eating a big breakfast (3 or 4 eggs, 1/2 cup plain oat meal, and fruit), then a small sandwich for lunch (meat, bread, nonfat cheese), and then a light, all-fiber dinner, I've managed to stay around 175-185 lbs with 5-6% bf.... At age 42! I usually have 2 or 3 snacks between those meals, usually a packet of raw walnuts, or maybe a bagel with natural honey, or Triscuits, etc... Also NO alcohol, NO chips or fries, and NO McDonald's. If you over-eat at any of your meals though, all bets are off. Discipline, discipline, DISCIPLINE!
If I were to skip meals, or go fasting, I'd have a beer gut in no time, and lose my current 5.3% bf status quickly! A body's natural defense to starvation is to store fat, and you can either fool your body into storing up masses of fat, thinking it's going to get starved to death by fasting... OR, you can fool it into thinking it's never going to starve, and making it have no need to store anything, by eating many small meals. Your body can't tell HOW MUCH you eat at each meal; only that it either has or has not been fed. Ever notice that if you are hungry, and you sit down with a huge plate of food, take a few bites and something happens to pull you away from your meal for a half hour (door bell, etc.), then you finally get back to the meal and you aren't hungry anymore. After 20 minutes from the first bite of food, your body says "OK; hunger satisfied. Something was eaten".
Just my personal success secrets after repeated failures.
Charles