Rabbit starvation

Protein poisoning (also referred to colloquially as rabbit starvation, mal de caribou, or fat starvation) is a rare form of acute malnutrition thought to be caused by a complete absence of fat in the diet.

Excess protein is sometimes cited as the cause of this issue; when meat and fat are consumed in the correct ratio, such as that found in pemmican (which is 50% fat by volume), the diet is considered nutritionally complete and can support humans for months or more. Other stressors, such as severe cold or a dry environment, may intensify symptoms or decrease time to onset. Symptoms include diarrhea, headache, fatigue, low blood pressure, slow heart rate, and a vague discomfort and hunger (very similar to a food craving) that can be satisfied only by the consumption of fat.

Protein poisoning was first noted as a consequence of eating rabbit meat exclusively, hence the term, "rabbit starvation". Rabbit meat is very lean, commercial rabbit meat has 50–100 g dissectable fat per 2 kg (live weight). Based on a carcass yield of 60%, rabbit meat is around 8.3% fat. For comparison, in terms of carcass composition, beef and pork are 32% fat and lamb 28%.

It has been observed that the human liver cannot safely metabolise much more than 221–301 g of protein per day (for an 80 kg/176 pound person), and human kidneys are similarly limited in their capability to remove urea (a byproduct of protein catabolism) from the bloodstream. Exceeding that amount results in excess levels of amino acids, ammonia (hyperammonemia), and/or urea in the bloodstream, with potentially fatal consequences, especially if the person switches to a high-protein diet without giving time for the levels of his or her hepatic enzymes to upregulate. Since protein only contains 4 kcal/gram, and a typical adult human requires in excess of 1900 kcal to maintain the energy balance, it is possible to exceed the safe intake of protein if one is subjected to a high-protein diet with little or no fat or carbohydrates. However, given the lack of scientific data on the effects of high-protein diets, and the observed ability of the liver to compensate over a few days for a shift in protein intake, the US Food and Nutrition Board does not set a tolerable upper intake level nor upper acceptable macronutrient distribution range for protein.

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