a whole cluster of reasons!!
yes, weight loss, for sure. but i also like fasting, even the weak, hungry feeling. i mean, at the same time as its torture, i also love it. i love feeling sick and struggling with basic tasks. and i love the headspace i get into, where everything seems very slow and solemn, even a blink of an eye has a certain sombre majesty to it when you're fasting. it's this almost religious feeling that usually sustains my fasting, even more than the promise of weight loss, which starts feeling improbable after a while, even though you are literally losing weight every day. plus, i get that fasters high REALLLLLLL good. i havent got it yet though. this time feels different, im much hungrier and weaker, almost couldnt get out of bed this morning, and it's only day four!!! so i dont know whats up with that. dont feel sick or dizzy though (which would be a sign of high toxicity), just hungry and weak.
why did you do it? also, if you're going to go sixteen days without food, aside from a banana here and there, you need to cut out the banana. that will kick you out of ketosis and no longing have access to your body's nutrient stores, you will go into starvation mode, and that is BAD.