Wa'il, if 0.6g of protein per pound of LBM sends one in a starvation mode, then even the zone becomes a ketogenic diet for them. the zone recommends anywhere from 0.6 to 1.25g of protein per pound of LBM, depending on level of activity and other metabolic demands. My LBM is about 90lbs, my protein intake is about 75g per day or higher(0.8-1g of protein per pound of LBM). I am not in ketosis, therefore I conclude that my sometimes 900cal per day zone diet is not a starvation diet and not a ketogenic one.

I am not sure why exactly you were in ketosis... something might have brought your blood sugar levels too low for your body to secret ketones as fuel for the brain. do you have reason to think that you have been producing ketone bodies as part of hormonal/metabolic imbalances, not only because 0.6g of protein were too few for you and sent you into starvation mode?

the solution for ketosis on the zone, if one wants to avoid it, is not just upping carbs, for many people are sensitive to carbs and stay on the zone precisely for diabetes control, etc. but
1) finding your own zone, as you've seen from the graph, the zone is wide, and 40/30/30 is only the point of entrance, but not everyone's sweet spot
2) gradually increasing total caloric intake (up to 10 times total body weight in calories) while monitoring bodyfat loss and supplementing with up to 5g of long-chain omega-3 fatty acids from various sources daily, exact amount of supplementation depends on the person's TG/HDL ratio. usually the problem resolves itself within one month and one can return to the lower caloric and omega-3's intake for enhanced bodyfat loss.