The Carnivorous Diet & Your Thyroid: Addendum
Wednesday, December 9, 2009 at 10:21PM 
A few forum members have pointed out that very low carbohydrate diets cause an elevation in reverse T3 (inactive T3 thyroid hormone). Apparently this is the reason everyone MUST EAT 50 grams of carbohydrates a day.
I will state here, I am not an expert and I don't pretend to be. My point of interest is that zero-carbers have a high success rate. The proclaimed crashing of the metabolism due to elevated reverse T3 does not jive with the real life results. I also reject the idea that low-carbers need to take thyroid pharmaceuticals to be healthy.
Here is a snippet of the study that's being tossed around.
Starvation has a profound effect on thyroid function, causing a decrease in serumT3 concentration and a reciprocal increase in rT3 level. These changes are due to a selective inhibition of the 5’-monodeiodination of iodothyronines by peripheral tis-sues. Reduction in carbohydrate intake rather than total calorie deprivation appearsto be the determinant factor. These alterations in thyroid function are believed to re-duce the catabolic activity of the organism and thus to conserve energy in the face of decreased calorie intake. Chronic malnutrition is accompanied by similar changes.Over feeding has opposite although transient effects.
But wait, there's more.
To evaluate the effect of caloric restriction and dietary composition on circulating T3 and rT3 obese subjects were studied after 7-18 days of total fasting and while on randomized hypocaloric diets (800 kcal) in which carbohydrate content was varied to provide from 0 to 100% calories. As anticipated, total fasting resulted in a 53% reduction in serum T3 in association with reciprocal 58% increase in rT3. Subjects receiving the no-carbohydrate hypocaloric diets for two weeks demonstrated a similar 47% decline in serum T3 but there was no significant change in rT3 with time. In contrast, the same subjects receiving isocaloric diets containing at least 50 g of carbohydrate showed no significant changes in either T3 or rT3 concentration. The decline in serum T3 during the no-carbohydrate diet correlated significantly with blood glucose and ketones but there was no correlation with insulin or glucagon. We conclude that dietary carbohydrate is an important regulatory factor in T3 production in man. In contrast, rT3 concentration is not significantly affected by changes in dietary carbohydrate. Our data suggest that the rise in serum rT3 during starvation may be related to more severe caloric restriction than that caused by the 800 kcal diet.
What we have here is two seemingly good studies, in complete opposition of each other. The later was specifically conducted with individuals eating a zero carb diet.
Both of these studies do not include what the rest of the diet was composed of. Without knowing what the subjects ate, we are left guessing whether they were predominantly eating fat or protein. Dietary fat, the critical macro nutrient for maintaining the health of the adrenal glands, seems like it could potentially alter any outcome of a stress related study.
Again, blaming the lack of the macro nutrient, that likely was the cause of the derangement in the first place is pretty silly. Those with thyroid disorders should be far more concerned with the intimate connection between insulin resistance, cortisol and reverse T3.
The stress hormone cortisol blocks production of T3 and causes an increase in the production of inactive reverse T3. Elevated levels of insulin lead to the over-arousal of the sympathetic nervous system (SNS). Chronic over stimulation of the SNS leads to the unnecessary production of cortisol, pooped adrenals, and eventually a sluggish thyroid.
HIGH BLOOD SUGAR > INSULIN > SNS HYPER-FUNCTION > ANGIOTENSIN II > ACTH ACTIVATION > UNNECESSARY CORTISOL > REVERSE T3
My stream of thought:
- Ditch the carbs.
- Eat until satisfied.
- Eat mostly fat, moderate protein.
- Get enough sleep.
- Take your vitamin D.
- Stay away from gluten.
- Call it a day.
Reader Comments (2)
It's so hard to apply scientific studies to long term carnivores. The studies used are usually less than 2 months and that is usually the period that people go through all kinds of induction symptoms so It makes sense that the results tend to be negative. The body does stabilize on a carnivorous diet and this has been proven with the Bellevue Trial. Unfortunately it seems that the results of the Bellevue Trial have already been forgotten by so many people.
I personally think It's amazing that both of Delfuego's kids have lived on nothing but pemmican since birth and have never needed a doctor because they've never been sick! Yes, I understand that it's not really scientific but to me never being sick are some impressive results!
Thanks for commenting CMR,
I whole heartedly agree about Delfuego's story, all of it is pretty incredible.
Unfortunately I'm one of those people that consistently forgets about about Bellevue!
Here is a refresher:
SUMMARY AND CONCLUSIONS OF THE ONE YEAR ALL MEAT TRIAL
1. Two men lived on an exclusive meat diet for 1 year and a third man for 10 days. The relative amounts of lean and fat, meat ingested were left to the instinctive choice of the individuals.
2. The protein content varied from 100 to 140 gm., the fat from 200 to 300 gm., the carbohydrate, derived entirely from the meat, from 7 to 12 gm., and the fuel value from 2000 to 3100 calories.
3. At the end of the year, the subjects were mentally alert, physically active, and showed no specific physical changes in any system of the body.
4. During the 1st week, all three men lost weight, due to a shift in the water content of the body while adjusting itself to the low carbohydrate diet. Thereafter, their weights remained practically constant.
5. In the prolonged test, the blood pressure of one man remained constant; the systolic pressure of the other decreased 20 mm. and the diastolic pressure remained uniform.
6. The control of the bowels was not disturbed while the subjects were on prescribed meat diet. In one instance, when the proportion of protein calories in the diet exceeded 40 per cent, a diarrhea developed.
7. Vitamin deficiencies did not appear.
8. The total acidity of the urine during the meat diet was in- creased to 2 or 3 times that of the acidity on mixed diets and ace- tonuria was present throughout the periods of exclusive meat.
9. Urine examinations, determinations of the nitrogenous constituents of the blood, and kidney function tests revealed no evidence of kidney damage.
10. While on the meat diet, the men metabolized foodstuffs with FA: G ratios between 1.9 and 3.0 and excreted from 0.4 to 7.2 gm. of acetone bodies per day.
11. In these trained subjects, the clinical observations and laboratory studies gave no evidence that any ill effects had occurred from the prolonged use of the exclusive meat diet.