I've never
willingly restricted the amount of protein I eat - I agree with
@Bluetit1802 that i'ts essential to maintain our bodies. My husband used to cook for both of us after he retired, andt he could be a real cheap skate with protoein, and I definitely siuffered from the lack before I begain to cook for myself again. So I eat low carb (generally under 50g carbs a day), adequate protein, and enough full fats to keep me from hunger.
Going down very low carb 20-25g carbs a day got me into ketosis, and continued low carbing re-started my body in fat burning mode, which I now believe is more important than actually being "in ketosis". My body uses whtever source of fuel is to hand, preferentially the few carbs i eat because they are quick and easy to process, then dietary and stored fat. I go in and out of ketosis, usually at fairly low levels and according to what fuel is currently available. Once our bodies are fat adapted (which is our natural state unless we are scoffing high carb foods like there's no tomorrow!), ketosis shouldn't be a real issue - IMO!
Roobbity