How can I ask my boyfriend to get fat?

I have been in a relationship with my boyfriend for over a year and love him very much even though he is underweight. He is a terrible eater and hates any form of fruit or vegetable. He's 176cm tall yet only 54kg and has even gone down to 50. He doesn't have a great appetite and that makes him skinnier. His lifestyle is also not very good. He works from home sitting down all day and doesn't do much so he doesn't get much exercise.<br><br>I know him gaining a bit of weight would be good for his health.<br><br>But, I've always had a thing for fat men. There's something about them that I just find so attractive. I have been finding myself looking at pictures of fat men to be honest.<br><br>I want him to be more fat, but am worried about asking him and him being offended. He's never really had an issue with my weight, which is good. I just want to help him gain some weight and am asking if anyone has any advice on how to ask him without him being offended.<br><br>TLDR! I want my boyfriend to get fat and am looking for advice.