I think that this is a valid question for physical fitness here is why.
When you're out of shape and overweight you focus on two things: You're weight and you're muscle tone. The more you eat(to a certain extent) the more your body has to work with(as far as energy for exercise, and protein for repairing muscles after exercise).
Most of my experience with people trying to build muscle or get back in shape is that people go through cycles, either bulking up to build muscle or slimming down to reveal tone. I think this is a big part of looking good, do you eat lots and gain muscle mass or eat very little and slim down.
My answer from personal experience is that you need to have enough energy to do your daily tasks, and to plan for physical activity. It's ok to eat less than what your body needs to maintain it's weight if you want to lose weight, but you need to consider that you'll be losing muscle mass as well when you do this. Muscle mass burns more calories while you're idle, it also makes your body have good shape and look toned. It's also ok to eat more than your body needs when you're trying to gain muscle mass.
The balance is something only you can figure out. Personally I think that going though a muscle building cycle for 3-4 weeks, then a cardio/slimming cycle for 2-3 weeks is where I found my balance.
Eating more small meals spread throughout the day and a larger one before and after a workout is in my opinion(and many others) the way to manage you're food intake. I strongly believe in a low carb higher protein diet, but again, some people feel differently(distance runners?). The very way the human body works lets us know that when we fast the body stores the remaining energy and weakensd the ability of the mind to think quickly, so I'm pretty against the idea of fasting.
Consider that always trying to lose weight or maintain a weight may not be what makes you look good, looks aren't based on numbers, so if you only base your routine by number of carbs or meals and not improving what you see in front of you'll always be slightly disappointed in what you see.
That's just what I've learned about my body from the past decade. I hope it helped you out. Also if you tell me a bit more about your exercise routine and goals I can change my answer to further help you.