[Evgeny]

I guess technically you are right, even meat has some carbs in it because muscles hold some glycogen.

The closest thing I can quote is the experiment that Vilhjalmur_Stefansson and Karsten Anderson took part in, eating only meat for a few years

https://en.wikipedia.org/wiki/Vilhjalmur_Stefansson#Low-carb...

http://inhumanexperiment.blogspot.com.cy/2009/09/two-brave-m...

In the end, the one-year project stretched to four years, during which time the two men ate only the meat they could kill and the fish they could catch in the Canadian Arctic. Neither of the two men suffered any adverse after-effects from their four-year experiment. It was evident to Stefansson, as it had been to William Banting, that the body could function perfectly well, remain healthy, vigorous and slender if it used a diet in which as much food was eaten as the body required, only carbohydrate was restricted and the total number of calories was ignored.

[dualogy]

> I guess technically you are right, even meat has some carbs in it because muscles hold some glycogen

Near-zero because muscle glycogen is used up upon death in a process called "rigor mortis" (not the case for liver glycogen however AFAIK). The fatty marbling luckily remains.