Regarding your BFF and her possible proposal to her lard loving lover, any chance you could find an excuse to pop on Super Size Vs Super Skinny or something similar that casually details the horrors of obesity one day when she's visiting you? Just as background stuff, or even be super subtle and if you're meeting her soon, on your way to meeting her pick up some god awful rag mag that has a front page headline about obesity (Pick Me Up used to have headers with stuff like "Help! My partner's (literally) suffocating me!"), that you can casually leave within eye shot for her, and if she sees it, you can gush about how terrible the story is, the person lost their legs, or went blind or something. Then you can segway into a conversation about how you're extremely concerned about the sky rocketing number of UK citizens who are on their way to an early death, or someone you know who's parent or grandparent is an utter invalid as a result of complications related to their obesity and how that person you know is suffering so much, as is the rest of their family, in trying to help their incapacitated obese family member.  That is, as long as she does't know you're a shit lord. If your identity is safe, plant a seed and sit back and let it grow.