Muscle/Fat balance while maintaining.

I tried on google, but among all the get-slim(rich)-quick diet sites I couldn't find very much in depth scientific information on exactly how fat and muscle is created/torn down while on maintenance.

For example, if one eats a little over their maintenance calories one day, then a bit under the next(as we all do if we are maintaining), would half the tissue you burn off on the below maintenance day come from muscle, leaving you with half of the fat you put on the day before? How does muscle tissue replenish itself? I keep hearing that you need to lift weights and consume an excess of calories to build muscle, but surely some must be built up under normal conditions to prevent us from withering away.

I ask because I was forced to abandon my fat loss goals and enter maintenance mode because my weight dropped too low, despite that fact that I haven't yet lost all the fat I wanted. I plan on doing weights to build back my lost muscle(and then some) to help me deal with fat, but I don't have time to make such a radical lifestyle change until this semester is over. Basically my worry right now is that on the days I overeat I will gain fat, and the days I undereat I will lose muscle, resulting in a lowering muscle/fat ratio. I realize that it is impossible for this continue indefinitely, but I'm curious know where the body draws the line with regards to how much fat it will store and how much muscle it will burn while generally on a maintenance intake.

I'd appreciate any pointers in the right direction.

I'm not sure, but you could try posting in Fitness - melkor and some of the others might have a better answer.

It's generally easier to gain and lose fat & fluid than it is to gain and lose muscle.  If you're on a maintenance intake the fluctuations you'll see are more likely to be fat & fluid, therefore.  To lose muscle (wasting) you have to be completely inactive and/or severely undereat.   You can tone up the muscles you've got at any time.  However, if you want to build muscle you need to be consistently at or above your maintenance intake.   You're not going to lose muscle by going a little below but you're not going to build any either.

If you can't get to a gym you can still do resistance exercises at home.  You can use simple hand weights, walls, chairs, floors.... be creative.

If you aren't doing high intensity cardio/major calorie deficit i wouldn't worry about it!

I'm maintaining....but i do a lot of high intensity cardio...(which obviously depletes muscle if you are eating low calories).....so i try to lift 8-12 pound weights doing squats lunges etc....if your scared about losing muscle i would suggest focusing on your legs doing these type of exercises ....focus on your legs...they're the biggest muscle group....If you want to keep muscle/don't have much time start from there.