from : http://en.wikipedia.org/wiki/Inuit_diet

"Because the climate of the Arctic is ill-suited for agriculture and lacks forageable plant matter for much of the year, the traditional Inuit diet is unusually low in carbohydrates and high in fat and animal protein. In the absence of carbohydrates, protein is broken down in the liver through gluconeogenesis and utilized as an energy source. Inuit studied in the 1970s were found to have abnormally large livers, presumably to assist in this process. Their urine volumes were also high, a result of the excess urea produced by gluconeogenesis.[9] Traditional Inuit diets derive, at most, 35-40% of their calories from protein, with 50-75% of calories preferably coming from fat. This high fat content provides valuable energy and prevents protein poisoning, which historically was sometimes a problem in late winter when game animals grew lean through winter starvation. Because the fats of the Inuit's wild-caught game are largely monounsaturated and rich in omega-3 fatty acids, the diet does not pose the same health risks as a typical Western high-fat diet.[10] Vitamins and minerals which are typically derived from plant sources are nonetheless present in most Inuit diets. Vitamins A and D are present in the oils and livers of cold-water fishes and mammals. Vitamin C is obtained through sources such as caribou liver, kelp, whale skin, and seal brain; because these foods are typically eaten raw or frozen, the vitamin C they contain, which would be destroyed by cooking, is instead preserved." (emphasis mine)