If your body is already used to using fat as a fuel, you won't necessarily get a big withdrawal from reducing carbs. Everyone is different!

Personally I find that having some sweet stuff is way more difficult than having none. Once I've allowed a bit of transition time (a week? 10 days?) zero carb is easier for me than low carb. On low carb I'm constantly fighting the impulse for a second piece of apple or dark chocolate - because I can easily inhale a whole dark chocolate bar - whereas once I've transitioned to carnivore I just don't really care about sweet tastes anymore. (Which begs the question of why I left carnivore a few times! I may post about that soon.)