My friend makes me look ugly?

You know how people say, when you chill with someone ugly it makes you look better? Yeah well that doesn't apply this time. I think it's because he's a boy and i'm a girl. My friend, is really bad looking. He even knows it and he's trying to lose a lot of weight to look better. He dresses sloppy with dingy looking clothes. He has pimples, dirty teeth, messy dirty blonde hair, He's on the fat side, and he walks slouching down so it looks like he has a hunch back or it looks like somethings wrong with his neck. I never made friends with people like this originally, but he gets teased a lot at school and I think it's messed up when people get sh*t like that cause they aren't as attractive. It's not like they aren't aware that they look that way. He actually even kind of hates himself. Genetically he's not ugly though. He just needs a make over. I just met him this year, really I started hanging out with him cause I felt bad but getting to know him though hes a nice kid. A little dull, too afraid of people and the outside world really, but he's nice. He's my friend now. The thing is I feel funny going outside with him and getting seen by people who don't know us. In school it's what ever. People know who I am, know what I'm about. But in the street being with him isn't such a good look. Keeping it real right now, it makes me look like a loser. I mean like really he told me that on some occasions people called him ugly out in the street, and some girl in a car started making fun of him, so he's like one those people who when you see them you think Oh my god why would you let your self go like that. It's very, very, obvious. I don't wanna hear sh*t from people saying this is shallow cause no it's not. I'm still his friend, I'm still nice to him, but I'm not gonna stop thinking about myself too, and right now, thinking about myself I know for a fact being next to him is affecting my self image. I don't mind chilling with him and a group of my own friends but when it's just me and him I feel like people are getting the impression we're some losers. And when I see our reflection that's really what it looks like. When I'm with a girl that's not as attractive I don't get this though? I think it's cause we're the same though. Well what do I do? He wants to start looking better...it would probably take a real professional to fix him though but I could help. Should I? Or would that seem like I'm trying to change him too much. Should I just text him and talk to him on the phone or only hang out with him when I'm in a group so it doesn't look bad, or should I just stop chilling with him all together? He's a nice kid, so regardless I'm gonna talk to him, I just don't know what to do when it comes to hanging out with him.