Why did I get body fat back?!

Why did I get body fat back?

I don't understand this

When I was in the hospital I basically didn;t eat for a few days, and I looked at myself and I could see that I had lost weight, like when i bend my arm theres not as much fat on the sides, and theres not as much fat on the side of my leg, but its wierd like the minute i started eating food again I noticed all the little flab came back in like 2 seconds, I noticed it as soon as I looked as myself after I ate my first meal,

I'm not overweight but its just wierd that this happens could you explain it? I was hoping to keep all that weight off

I would imagine you weren't very active while you were in the hospital? You likely lost some water weight, and probably a little muscle tone, depending on how long you were there. Water weight isn't true weight loss, and comes back very quickly. By building up muscle, you'll boost your metabolism and be able to burn calories faster, even at a resting rate. When you lose muscle and/or starve yourself, your metabolism will slow down.