I'm asking this question on behalf of my roommate. Obligatory pre emptive to whoever says this is from me

Ok he met this girl that he likes but shes fat. Everything else about her is good. They are both in their early-mid 30s, both are financially stable, both the type of people that always get that "they're a nice person" statement said about them.

Is there any way to make a fat chick lose weight without it becoming a apocalyptic nuke fall out in their relationship?