So I whipped up this lazy thing BUT, people have been wondering how my Princess Powers kick in all this. My powers are fueled by (you guessed it), fat. This offers a significant balance on power on my behalf. I am able to fly with extremely heavy weights, but during flight my weight will drop slowly. This goes the same for magic, if I want to a high-powered spell, I have to have the weight to back it up. Quickly my weight will go down, but this is remedied with eating food, mainly sweets. Anything (edible/food) is quickly turned to fat... and it doesn't take too large of amounts to do so either (you know, so to not cause a famine).
This cycle prevents me from having too much power, meaning I have to have an emergency stash of food in emergencies, and it still takes time to eat and grow. Also to note that with flying, once I'm down to a certain weight, it will no longer make me lose it since the wings can operate on their own. The same goes similar with magic, will start to use with mental strength, though with both: can be boosted as long as I'm not regular/skinny... there is a stopping point.
This is all the knowledge I have so far, I'm still quite new to the Princess stuff so there's a lot to learn. Here in the Sweet Kingdom lies more secrets onto what I can do, this is just what has been shown to me so far. I hope this helps all of you who wanted to know~