Carbs shouldn't be at zero, I found. The problem is when we 'cheat' for carbs, we tend to cheat with the worst carbs. We eat some potatoes, fried in seed oils, etc. Very little potatoes are a giant amount of carbs. I can't eat potatoes at all or it's too many carbs.
I found that adding measured carbs stopped my weight loss on Keto/Carnivore.
I added Basmati long grain white rice in a very small amount. Very easy on my digestion, too. Just to keep me out of fat burning during the busiest part of the day.