Feeder fantasy help

So I just started dating a guy and we recently had a discussion about our sexual fantasies. His biggest fantasy is that I gorge myself on food and gain weight, especially on my stomach. I'm 5'2" and 105 lbs. Not exactly chubby. He says that he's attracted to me as is, but would love it if I gained weight. I'm really unsure of how to handle this situation and would love to hear from guys who have similar fantasies.