Explorers also understood the dangers of consuming only lean meat. Vilhjalmur Stefansson wrote as follows:
"The groups that depend on the blubber animals are the most fortunate in the hunting way of life, for they never suffer from fat-hunger. This trouble is worst, so far as North America is concerned, among those forest Indians who depend at times on rabbits, the leanest animal in the North, and who develop the extreme fat-hunger known as rabbit-starvation. Rabbit eaters, if they have no fat from another source—beaver, moose, fish—will develop diarrhea in about a week, with headache, lassitude and vague discomfort. If there are enough rabbits, the people eat till their stomachs are distended; but no matter how much they eat they feel unsatisfied. Some think a man will die sooner if he eats continually of fat-free meat than if he eats nothing, but this is a belief on which sufficient evidence for a decision has not been gathered in the North. Deaths from rabbit-starvation, or from the eating of other skinny meat, are rare; for everyone understands the principle, and any possible preventive steps are naturally taken."
"We were here able to buy some biscuit. I had now been several days without tasting any thing besides meat: I did not at all dislike this new regimen; but I felt as if it would only have agreed with me with hard exercise. I have heard that patients in England, when desired to confine themselves exclusively to an animal diet, even with the hope of life before their eyes, have hardly been able to endure it. Yet the Gaucho in the Pampas, for months together, touches nothing but beef. But they eat, I observe, a very large proportion of fat, which is of a less animalized nature; and they particularly dislike dry meat, such as that of the Agouti. Dr. Richardson, also, has remarked, “that when people have fed for a long time solely upon lean animal food, the desire for fat becomes so insatiable, that they can consume a large quantity of unmixed and even oily fat without nausea:” this appears to me a curious physiological fact. It is, perhaps, from their meat regimen that the Gauchos, like other carnivorous animals, can abstain long from food. I was told that at Tandeel, some troops voluntarily pursued a party of Indians for three days, without eating or drinking."I found a very good description of the symptoms here (article by Jessica Ellis).
"The mechanics behind rabbit starvation are fairly simple. Protein in the body is converted into glucose by the liver, and can be burned as energy. The liver, however, can only safely process a limited amount of protein at a time. If the body receives more protein than it can safely turn into glucose, the resulting strain on the liver and kidneys can cause an increasing buildup of ammonia and amino acids. The liver then flushes these excess byproducts into the bloodstream, causing dangerous and even fatal consequences.
In addition to straining the liver, protein over-consumption also causes various symptoms of malnutrition, including fatigue, nausea, diarrhea, and constant hunger. These symptoms occur because the body is being deprived of necessary nutrition provided only by fat, carbohydrates, and micronutrients such as vitamins. Symptoms will occur regardless of how many calories a person experiencing rabbit starvation eats, since the body is limited in its ability to process energy and nutrition from protein. Thus, a person can be eating an enormous amount of food, yet still experiencing weakness, hunger, and other malnourishment symptoms.
The possibility of rabbit starvation leads many health experts to counsel against some protein-heavy diet regimes. Although the exact upper limit for safe protein consumption is not widely agreed upon, some authorities suggest that protein poisoning becomes a concern if protein comprises more than 35% of daily calorie intake. Some suggest that high-protein diets should be monitored by a doctor or dietician to prevent rabbit starvation from taking hold."