Those skinny bastards try to say the right thing. They want to encourage you, right. But sometimes what they say and what I hear are two completely different things. Maybe I'm just an oversensitive bitch, but mostly this stuff is just plain patronising. For example:

You look so healthy - you are so overweight, I'm surprised you aren't dead yet.

She was so big, she'd be two of you - look skinny dudes, you might think that it is reassuring for us to know that, while we might be big, there are folks out there even bigger but personally I don't want to be your measuring stick for largeness.

A friend of mine was telling me about a really good diet - trust me, we've heard all about it. We probably lost and regained the weight from that same diet ten years ago.

and, the all time favourite:

You'd be so pretty if you lost some weight - if I even need to explain what is wrong with that then you are never going to get it. I think anyone that has ever said that to someone in their life should be put on one of those force feeding machines they use to fatten up geese for pate in France and bloated up to about 300 kgs then parade in freak show. That'd learn them.