That's called "rabbit starvation". It got that name because it happens to people who are stranded or lost somewhere and survive for weeks on very lean animals like rabbit, for example. It's basically protein poisoning. It has something to do with a lack of fat in your diet. Hopefully neither will ever need to but they recommend consuming the bone marrow and organs to get as much fat as you can. In normal life there is no risk of that unless you're some kind of lunatic.