I want to eat after an old lady told me to stop
Why must you? That's why you want to eat?
Yes, how else am I going to prove my point that I can eat for hours.
You can eat for hours, but that isn't very healthy. Elders have a lot of knowledge so you should listen to them. You can get sick from over eating, although it feels good to be stuffed right now.
She's fat so I'm going to eat as much as I want.
I don't think her weight has any bearing on what you can do, she's just trying to look out for you so you can be as healthy as you can. Like I said, old people know a lot so try listening to her and make her proud of what you can do.