Thank you so much for all of these varied responses! I read the thread eagerly as it unfolded, but never really got a chance to sit down and reply.
agouderia - your approach is probably the one that's always worked best for my lad, so it's one I try to persist with. I'm a language freak too, so at least I feel confident that I'm up to the task of choosing precisely the right phrasing in most compliments, and I do try to run with the "big, broad, safe, strong" phrasing whenever I can. It helps that he actually is very strong, so he does find that believable, not just euphemistic. (I'm also particularly grateful that you replied to this post, having just come off the high of reading your story Available In All Sizes. Good with words indeed!) You're also right in pointing out that responding to compliments is a conditioned thing based on past experience - I'm not a thin girl myself, and I have all the requisite baggage that comes with being about an Australian size 14 (you know, not actually what most people call fat, but only because they think fat is an insult as opposed to a descriptor ), so I have good and bad days accepting compliments too. He and I will have cute arguments with each other, to the tune of, "Ok, if I accept that you think I'm hot, then you have to accept that I think you're hot!" "Oh fiiiine."
djudex, thank you! Nanny Ogg's such a delight of a character, isn't she? I just love how relentlessly cheery and lascivious she is, how she brings people together and doesn't give a fuck, especially in her appearance in I Shall Wear Midnight.
To the multiple people who advocate being honest to a fault: I both agree and disagree. My lad does know exactly what I like about him physically, including his size and his shape, and has known basically from the beginning (a cute story, but probably not all that relevant to the thread), especially because I can't stand to hear him put himself down, so I would never have been able to keep quiet when he was complaining about not liking himself in the mirror on some particular morning. But I also don't really like the idea of calling him a "fat fuck" or similar - each to their own, of course, and I love that it works for other people, but I just know certain phrasings would hurt his feelings more than swell his pride, so even though I absolutely believe in being honest, it's also really important to me to choose my words to make him as happy as me. After all, a compliment is about making someone else feel good as much as about expressing myself, probably more the former than the latter, and those words wouldn't make him happy.
Sasquatch - he's actually pretty good with taking compliments these days, now that he believes me, and that only took a relatively short while - maybe a few weeks. It's just that he believes I'm nearly the only crazy girl he's ever met who likes his body, rather than tolerating him despite it or being repulsed by it. I know there's not much I can do about that, though I wish there was!
Those who mentioned objectification - I have to be honest, I actually kind of like being periodically objectified, as long as it's by someone who also likes me as a human being with a personality. It's nice to know someone likes your physicality on a visceral level, not just you as a set of emotions or a disembodied brain in a jar or whatever. So I don't think objectifying compliments are bad, as long as they aren't the only kind given.