I think I remember reading the minimum amount to maintain nitrogen balance was .8 per kg, but that was not conducted on LC subjects.

Since you can assume some protein will be used for fuel on this diet, I wouldn't drop below a protein ratio that is 40% of your daily calories ... about 5% is carbs, and the rest -- 55% -- is fat (25% unsaturated and some MCTs, 5% fish oils, and the rest being monounsaturated and saturated)