The real question one should ask is: What do you replace your carbs with? There are only three macronutrients, so are you replacing those zero carbs with protein (ie, low-fat/high-protein, which leads to nausea, diarrhea, weakness... aka rabbit starvation) or are you replacing them with lots of fat? I think insufficient fat may be the basis of problems some people have with zero-carb.

I've been zero-carbing off and on for over a year, on again for the last week and I feel great... lots of energy, sleeping well, continuing weight loss, don't miss carbs, etc. BUT, I keep protein around 15-18%, 1-2% inescapable carbs (yes, coffee is inescapable, LOL), with the balance in fat, around 80+%. With enough fat, you don't need fiber, at least I don't.

By the way, it's hard to truly zero-carb unless you eat nothing but meat and most fish... no eggs, organ meats or shellfish, among other things. I've been eating about 3-5 g carbs, mostly from eggs, coffee and 1-2 oz/day of cream for said coffee).