Most cheese is low in carbohydrates and according to one site it has almost no glycemic effect (b/c it's so low in carbs)
Lots of sources say most Cheese (except for Cottage Cheese and Feta and Parmesan) is not allowed:
Cottage cheese has been mentioned by Tim Ferriss, and others, to be OK as a last resort, or backup. This doesn’t mean relying on it every day...
Feta cheese has been argued by some people as being OK,...
Parmesan has been mentioned, in some recipes, .... Other than the 3 above, most other cheese should be avoided. In general, cheese packs a lot of fat, a small to moderate amount of protein, and the potential to delivery a lot more energy than you’ll notice, making it easier to overeat.
But that rational "too much energy" seems a bit counter to the "slow carb" diet. So I'm confused.