My Boyfriend calls me chubby all the time?

He always tells me I have fat fingers, chubby feet, chubby sides, a chubby stomach, fat knees and a chubby face. And means it. Every time I hangout with him he says something about it and it's making me contemplate on starving myself and that i'm not good enough or that he wishes that I was skinny, he's even asked me how much I've weight before. I already struggle with self image problems. It's not always about being chubby. He sometimes makes other rude comments as well.. (I don't really think he means to..) He also implies questions or statements to me all the time about weight, self esteem sometimes about our relationship ect. When I obviously know why he's asking them. I'm always wearing hoodies or layers so it's not as obvious and doesn't stand out to him so much. I'm 5'4, weigh 116 pounds and wear a size 3. I know that's a healthy weight, but I swear I don't look like it. Next time he says something offensive to me, what can I say to him? Why does he do this?