Seconding @Lithium. I tried this at one point, many years ago. Doctor and nutritionist's supervision and everything. Apparently, I am meant to be as much the carnivore as possible. We could not find a balance that worked, even with some absurd costs in supplements and such to try to help balance things.
Weirdly, my body processes cholesterol very effectively. I get liver stones but they pass quickly while small. Despite being overweight, other than blood pressure (which is on the high side of normal -- drinking 2 pots of coffee and smoking a pack of 12 cloves a day, no less), the hospital stay involved all the testing, and they were genuinely shocked by how ideal my numbers were. Blood sugar, cholesterol, etc. All not just normal, but good. It baffled the hell out of them, re: 'then how the hell are you a fat person!?' They expected very, very different results... and they were running all of these tests twice daily to check on all the things constantly. (Blood sugar was 6x/day, even.)
So, uh, this is the roundabout way of saying: YMMV, I'm a weird example apparently, but be prepared to run into some unexpected weirdness if you try it and keep in close contact with a nutritionist to monitor at least for a while as you start out, it can make a really big difference.' I almost passed out while driving once during this period, so... yeah. It's not just potentially feeling sick or not being at completely ideal vitamin levels to be careful about.