I'm a low carber, and if I eat something carb heavy (like potatoes or pasta) I get a badly upset tum, so I do my best not to. Rather than being a restrictive diet I find it easy and enjoyable (the first couple of weeks on this way of eating can be hard as you switch over). I still eat (and cook) things like bolognese sauce, and curries, but I use shredded lettuce in place of the rice or pasta - simple. It's really not difficult to cater for - eggs, cheese, green leafy veg, mushrooms, some tomatoes and onions, courgettes, aubergines, peppers, fish, seafood, meat and poultry, nuts, plus full fat unflavoured/sweetened yogurts, double cream, butter, olive oil - it's not difficult to make a meal out of that lot, with added carbs (bread, pasta, rice, pastry, potatoes etc.) for those who eat them. I probably eat far more vegetables now than I ever did when I was eating a standard diet. Don't steam your fish, OP, pan fry it in butter and add a cream-based sauce - delicious!
If the worst comes to the worst and I'm ever faced with a meal where it's impossible to avoid carbs (something like a risotto, maybe?) then I just wouldn't eat it - my appetite's under control on a low carb diet, so missing the occasional meal isn't really a problem. I'm struggling to recall a time when I've been put in that position, though. There's always a low carb option on a menu when eating out, and my friends know about how I eat, so tend to be nice enough to make sure there's suitable food available for me.
I've cooked for friends with various dietary preferences - vegans, veggies, low GIers, low fat eaters, calorie restrictors etc. - never yet found a diet that's impossible to cater for - you just have to like the people enough to be bothered and to want to give them something they'll enjoy. If you don't like your guests to begin with, you have to wonder why you're cooking for them in the first place!