Protein poisoning



Protein poisoning (also referred to colloquially as rabbit starvation, mal de caribou, or fat starvation) is an acute form of malnutrition caused by a diet deficient in fat and carbohydrates, where almost all bioavailable calories come from the protein in lean meat. The concept is discussed in the context of paleoanthropological investigations into the diet of ancient humans, especially during the Last Glacial Maximum and at high latitude regions.

The term rabbit starvation originates from the fact that rabbit meat is very low in fat, with almost all of its caloric content from the amino acids digested out of skeletal muscle protein, and therefore is a food which, if consumed exclusively, would cause protein poisoning. The reported symptoms include initial nausea and fatigue, followed by diarrhea and ultimately death.

Physiology
The U.S. and Canadian Dietary Reference Intake review for protein mentions "rabbit starvation", but concluded that there was not sufficient evidence by 2005 to establish a tolerable upper intake level, i.e., an upper limit for how much protein can be safely consumed.

According to Bilsborough and Mann in 2006, protein intake is mainly restricted by the urea cycle, but deriving more than 35% of energy needs from protein leads to health problems. They suggested an upper limit of 25% or 2-2.5 g/kg, "corresponding to 176 g protein per day for an 80 kg individual", but stated that humans can theoretically use much larger amounts than this for energy. For arctic hunter-gatherers, the amount can seasonally increase to 45%.