There's no need to believe or disbelieve. Vilhjalmur Stefansson and Karsen Anderson showed back around 1930 that it wasn't a special adaptation of the Inuit people. They and their fellow explorers of European descent were healthy on a diet of fish and meat. Stefansson spent 9 years of 11 years of Arctic exploration living on a meat diet.

As that possibility was widely disbelieved, the two of them spent a year on that diet in New York, with observers. See http://en.wikipedia.org/wiki/Vilhjalmur_Stefansson#Low-carbo... and the medical publication at http://www.jbc.org/content/87/3/651.full.pdf .

Others since then have done the same. Here's someone who's been on a meat diet for 5 years. http://www.vice.com/read/this-guy-has-eaten-nothing-but-raw-... .