Probably falls in the category somewhere with chubby and BBW. You are also asking if you are fat, fat is mostly used as very negative term which insults people instead of anything helpful. I hopy you don't listen to insulting people and let it influence the way you think about yourself.
I certainly am happy that you posted this because your ass and your body in this pic look sexy to me.
If you want to change something about your body then do it, but please love yourself regardless.
I only drink green tea, is your cock also better than that?