"...Eskimo women are sometimes grandmothers before the age of twenty-three, and that they usually seem as old at sixty as our women do at eighty." Vilhjalmur Stefansson (1935)
I've been getting a few emails about the carnivore diet, and I thought it might be useful to post some of my thoughts here if anyone was interested.
So, first, a little background: I consumed a "zero-carb" diet or carnivore diet (red meat and water) for about two years between 2008-2010. In fact, my website used to be called carnivorehealth (since then that URL has been purchased by someone else). Also, I was a heavy user of the zeroinginonhealth.com forum run by Charles Washington and had frequent correspondence with Joe Anderson (who was always really cool and never asked for anything in return).
I think my health was relatively good the first year coming from various restrictive diets (e.g., vegetarianism, veganism, low-carb paleo, keto paleo). However, the second-year shit hit the fan, and I started experiencing intense hypothyroid symptoms, which eventually led me to the work of Selye, Peat, Szent-Györyi, etc., and away from Internet diet war culture.
When a carnivore diet improves a person's health, I suspect it could be from a few different things:
- Removing hundreds of irritating additives in regular foods (e.g., gums, dyes, carrageenan, citric acid, etc.)
- Removing grains, beans, starches, and undercooked vegetables that can interfere with digestion by increasing bacterial endotoxin (lipopolysaccharide)
- Obtaining adequate protein (I talk to many people who eat less than 50 grams of protein per day)
- Removing added polyunsaturated fats in all forms and obtaining generous amounts of saturated animal fats
- Removing unneeded supplements that might have been doing more harm than good
- Becoming proactive about a health situation, which I think has a therapeutic effect by itself
I think the main long-term risk with dropping the carbohydrate content of the diet very low is a rise in the stress (or "adaptive" or "counter-regulatory") substances derived from the hypothalamus, pituitary, and adrenals that are intimately involved in all aspects of degeneration and aging. In general, carbohydrates suppress the stress systems:
“…Availability of simple carbohydrates, such as sucrose, provide a highly energetic, immediate and utilizable substrate that seems to be important during times of stress…” “This may explain why stress stimulates a preference, or craving, for nutritive carbohydrates.” Laugero, K.D. (2001)
"The counterregulatory hormones glucagon, adrenaline, cortisol and growth hormone are released during hypoglycemia [low blood sugar], and under other stress conditions.” “...Adrenaline becomes the most important hormone for glucose recovery during hypoglycemia.” "Cortisol and growth hormone contribute to counterregulation during prolonged hypoglycemia, but adrenaline is also of utmost importance in this condition.” Lager, I. (1991)
Oddly enough, running on a higher concentration of stress hormones can make a person feel good, at least, in the beginning:
“Adaptive hormones can cause mental changes in man. Many patients who take ACTH or cortisol first develop a sense of extraordinary wellbeing and buoyancy, with excitement and insomnia; this is sometimes followed by a depression which may go so far as to create suicidal tendencies.” Selye, H. The Story of Adaptation Syndrome (1952)
“Glucocorticoids exert early influences on the brain that tend to elevate mood and increase the sense of 'well-being.' Larger amounts can bring on temporary euphoria. However, the secondary effects include psychic depression. Patients with chronically elevated levels tend to have mood swings. They have been known to display bizarre behavior and to suffer hallucinations.” Martin, C. Endocrine Physiology (1985)
Image: Carnivore Diet advocate Shawn Baker loses it on a vegan person.
In a vicious cycle, hormones that rise during stress can suppress a person's thyroid function in order to slow the rate of metabolism and 'go longer on less.' I'm aware that a few people think that having slightly lower thyroid function is good for longevity; however, Chris Masterjohn has pointed out that a high metabolic rate, and the subsequent production of carbon dioxide, is necessary to use nutrients such as vitamin K optimally:
"The greater the supply of carbon dioxide, the better vitamin K can do its job. Because carbohydrates are richer in oxygen, burning them generates about 30 percent more carbon dioxide per calorie than burning fat, and low-carbohydrate diets have been shown to lower blood levels of carbon dioxide Thyroid hormone is a key regulator of the metabolic rate and may thus be a major determinant of the carbon dioxide available for activating vitamin K-dependent proteins." Masterjohn, C. (2013)
"The effect of a ketogenic diet on respiratory function - The metabolic effects of a ketogenic diet imply a higher-than-usual oxidation of fats, which leads in turn to reduced respiratory exchange ratio values [lower carbon dioxide]." Paoli, A., et al. (2013)
Besides a decreased concentration of carbon dioxide, another feature of a slower rate of metabolism is a higher level of cholesterol, which is normally turned over into substance that protect us from stress (e.g., pregnenolone, progesterone, and DHEA) in proportion to the thyroid function and nutrients such as vitamin A.
If a person's lifestyle was contributing to a slower rate of metabolism a higher level of cholesterol would be expected along with a decreased concentration of the protective steroids:
Image: Frank Tufano, and Tristan from Primal Edge Health, who both seem like cool dudes, consume their own versions of the carnivore diet and both sport higher levels of cholesterol suggesting that they are hypometabolic.
"Lipid levels increased in a graded fashion as thyroid function declined.” Canaris, G.J., et al. (2000)
"Thyroid administration produced a sharp drop in serum cholesterol in every case. This accompanied by a rise in the basal metabolic rate." Kenneth B., et al. (1939)
"...The decreased T3 seen in hypothyroidism may result in increased serum cholesterol." "Although a clear correlation exists between overt hypothyroidism and clinically significant hypercholesterolemia, there is a logarithmic relationship between thyroid-stimulating hormone and cholesterol, and the effects of subclinical hypothyroidism on cardiovascular disease are under debate. However, current data suggest that normalizing even modest thyroid-stimulating hormone elevations may result in improvement in the lipid profile." Feld and Dickey (2001)
"Serum concentrations of DHEA, DHEA-S, and PREG-S were decreased in hypothyroidism... Thyroid hormone may stimulate the synthesis of these steroids..." Tagawa, N., et al. (2000)
My buddy Lex Rooker who has been on a zero-carb raw meat diet for over a decade noticed that his TSH level progressively climbed when he was posting his lab work on the now-defunct rawpaleodiet forum. I don't consider the TSH to be a specific marker for thyroid function, but I do think it could be used as a marker for inflammation in some situations.
Speaking of Lex, he and I went to a zero-carb meet up in 2009 and were shocked when we realized that we were two of the only people doing the diet in a group of thirty people or so.
I don't regret dabbling in carnivory, but in retrospect, I should have told approximately no one what I was up to. My desire to integrate dietary movements into who I was made it challenging when I had to confront the uncomfortable reality that what I was doing wasn't working. If I had been regularly measuring my underarm temperature and resting pulse rate I suspect I might have been able to identify the impending danger of carbohydrate restriction sooner than later.
"Changes in body temperature are associated with significant changes in metabolic rate.” "Resting metabolic rate is largely regulated by thyroid hormones…” Landsberg, et al. (2001)
"Moreover, there is increasing evidence that thyroid hormones have direct chronotropic effect on the heart that are independent of the sympathetic nervous system." Polikar, R., et al. (1993)