Is a diet comprised solely of meat good for you? I think you know the answer.
I have been watching the National Geographic series of documentaries Life Below Zero, which features individuals who live (often alone) in harsh conditions in the Alaskan wilderness. They are self-sufficient, providing their own water, heat, shelter, and food. They harvest their own food by hunting, fishing, and trapping animals. One of them announced that meat is poison and recommended a diet of 70% fat. I questioned that but learned that he was probably right when it came to his own lifestyle in a sub-zero environment. But it can’t be extrapolated to apply to everyone.
Protein poisoning is a real thing. Also known as rabbit starvation syndrome, mal de caribou, and fat starvation, Wikipedia defines it as an acute form of malnutrition caused by a diet deficient in fat and carbohydrates, where almost all calories consumed come from the protein in lean meat.
Rabbits have very lean meat. Eating only rabbit meat can lead to “rabbit starvation” and death. Groups like the Inuit eat mostly animal products, but they get fats from blubber, bone marrow, organ meats, and the meat of animals that have considerable fat. For the Inuit, seal oil is a dietary staple, used as a dipping sauce. Subsistence hunters in the documentary series are shown eating some of their favorite parts of meat raw at the kill site. Raw meat is a good source of vitamin C, but cooking or drying meat destroys vitamin C.
The carnivore diet
There are many popular fad diets. One is the Carnivore Diet. “It aims for zero carbs per day. You eat only meat, fish, eggs and some animal products; you exclude all other food groups — including vegetables, fruits, grains, legumes, nuts and seeds.” Carnivore diet macronutrients call for 70-80% of calories from animal fat.
One advocate says “animal fat is likely the single healthiest and most beneficial nutrient in the human diet.” He describes the results of two large published studies that showed remarkable benefits. Subjects lost an average of 20 pounds, 96% had full resolution or significant improvement in all diseases, 92% of diabetics were able to stop using insulin, 93% had improvement in mental health disorders, and more.
Yes, studies have shown that the carnivore diet can significantly improve and even resolve numerous diseases, reduce medication use, improve gastrointestinal conditions, boost mental health, clear up skin conditions, reduce blood sugar fluctuations, and promote weight loss. But it can also cause harm. It is low in fiber and can cause side effects like constipation, diarrhea, nausea, hunger, sugar cravings, leg cramps, bad breath, and heart palpitations. Meat contains things that we know are bad for our health, like saturated fats and the high sodium levels in processed meats like bacon.
All carbs are not equal. Simple carbs (desserts, cakes, pies, etc.) often contain white sugar, flour, and preservatives They can cause inflammation and weight gain and contribute to diabetes, obesity, and high blood pressure. But complex carbs (fruits, vegetables, and whole grains) contain vitamins and minerals and micronutrients that are essential to health.
High protein diets … advocate excessive levels of protein intake on the order of 200 to 400 g/d … which may exceed the liver’s capacity to convert excess nitrogen to urea. Dangers of excessive protein, defined as when protein constitutes > 35% of total energy intake, include hyperaminoacidemia, hyperammonemia, hyperinsulinemia, nausea, diarrhea, and even death.
Protein intakes above 35% of energy needs have also been shown to decrease testosterone and increase cortisol levels.
Some people argue that humans should not eat meat at all, since they do not share the anatomic characteristics of carnivores.
Are humans herbivores or omnivores?
A related question is whether humans are omnivores or herbivores. I always assumed that it was obvious that we are omnivores. Vegans claim that we are anatomically herbivorous. We have short, soft fingernails rather than sharp claws. We are unable to kill animals with our bare hands and eat them raw. Our “canine” teeth are small. Our jaws move side to side and our back molars are flat, enabling us to grind fibrous plant foods. Our stomach acids are not as strong as those of carnivores. Our intestines are longer than those of carnivores, giving bacteria time to rot the meat, increasing the risk of food poisoning and colon cancer. T. Colin Campbell says “animal protein . . . is one of the most toxic nutrients of all that can be considered.”
On the other hand, “biological anthropologists would point out that the anatomy of our brains, teeth and intestines show that we evolved as highly resourceful and flexible omnivores who can adapt to many varied environments to meet our nutritional needs from both animals and plants.”
We may be anatomically more similar to herbivores than to carnivores, but we are functionally omnivores. History shows that humans have thrived on a wide variety of diets.
Conclusion: the carnivore diet is not healthy
A lean-meat-only diet can kill through protein poisoning. Fats and carbs are essential to providing all the nutrients and energy we need. A balance of protein, fats, and carbs is ideal, and that’s exactly what standard diet advice recommends.
This article was originally published in the Science-Based Medicine Blog.
