Thyroid function and saturated fatedwardjedmonds.com /thyroid-function-and-saturated-fat/

by Edward on 18/10/2014

A few years ago I came across this letter (Kasper, Schonborn, & Rabast, 1975). I was still in Germany atthe time and still fiddling with carbohydrates. I knew at the time that saturated fat increased thyroidhormone production and promoted an optimal metabolism because I was outside in the cold doing a lot ofrunning and when my carbohydrates got a bit higher than normal I wouldnt be able to run in freezingweather with shorts, no Id have to put the thermal tights on thus reducing me to a grade B bad ass insteadof grade A.

I remember this bit catching my attention at the time:

I filed it away in my brain.

Shortly after I remember coming across this paperthat proposed that iodine deficiency may be causedby an increase in carbohydrates (Kopp, 2004). Thisseemed to fit in with the theme: those energysubstrates that are efficient AND optimal are sobecause they require less overall cofactors to beoxidized and because they are the exact type ofresource desired by the mitochondria. Typicallyefficiency is the ratio of useful output to the totalinput in a system. Sure mitochondria can oxidizeother substrates, however, what you find is thatthose substrates namely the polyunsaturated fatsand carbohydrates tax the entire organism bringinginto the picture those hormones that otherwisewould be background which typically increase theneed for more energy. That bit therethathormones are background until undesirable energysubstrates are brought into the pictureis a keypoint to remember for future posts.

Recently I came across this paper (Yoshimura, Hori,& Yoshimura, 1972):

Ive come across several papers looking at the effects of macronutrients on thyroid hormones. The patternis that fat has the greatest impact on thyroid hormone production and that carbohydrate while it cantemporarily increase T3; the increase in T3 caused by increased carbohydrate consumption is actually aprotective measure, a symptom. A symptom that I think is best to avoid. Interestingly fat reduces anxietywhen compared to the other macronutrients which in my opinion points to stable thyroid hormoneproduction (Prasad & Prasad, 1996).

It has been shown that carbohydrate can increase RQ. Though this is often not clear cut it is the generaltrend that RQ increases with carbohydrate consumption. This is in my opinion a result of the Crabtreeeffect.

When carbohydrates are consumed T3 increases which results in an increase in fatty acid oxidation. Thisis curious because one might be so inclined to expect an increase in glucose oxidation. Instead whathappens is that fatty acid oxidation increases and so does DNL. Essentially carbohydrates are beingconverted to fatty acids, insulin is raised and the surplus of fatty acids is being stored, T3 if it can stay

elevated long enough tries to bring back energy balance by burning fatty acids. Of course overtime thisbreaks (pathological insulin resistance coupled with thyroid disorder probably leads to ketoacidosis) andresults in metabolic derangement not unlike how the pancreas breaks after a few decades ofhyperglycemia. The solution to this problem is to eat in a way that prevents the problem in the first place.

T3 also happens to stimulate mitochondrial uncoupling, the uncoupling effect is partially indirect and theresult of burning fatty acids. Uncoupling is for another time.

I think that when you base your diet off of saturated fat that ketones and glucose are spared in the rightamounts for the tissues that desire them, much like in neonates. I think that aging is mainly a defect in fattyacid metabolism not glucose metabolism. I think this is why our risk for cancer increases as we age, againCrabtree effect. Thyroid hormones keep the body organized i.e. saturated fat as the predominate energysubstrate keeps the body functioning properly, carbohydrates cause disorganization. For the most partpeople who live a long time like their fat, and when you see an exception my opinion is that they are goingthe naked mole rat route, they are eating carbohydrate but are actually fermenting it all to fatty acids andlike the naked mole rat are physiologically insulin resistant.

References

Kasper, H., Schonborn, J., & Rabast, U. (1975). Letter: Behavior of body weight under a low carbohydrate,high fat diet. The American Journal of , 28(8), 800801. Retrieved fromhttp://ajcn.nutrition.org/content/28/8/800.short

Kopp, W. (2004). Nutrition, evolution and thyroid hormone levels a link to iodine deficiency disorders?Medical Hypotheses, 62(6), 8715. doi:10.1016/j.mehy.2004.02.033

Prasad, A., & Prasad, C. (1996). Short-term consumption of a diet rich in fat decreases anxiety response inadult male rats. Physiology & Behavior, 60(3), 103942. Retrieved fromhttp://www.ncbi.nlm.nih.gov/pubmed/8873290

Yoshimura, M., Hori, S., & Yoshimura, H. (1972). Effect of high-fat diet on thermal acclimation with specialreference to thyroid activity. The Japanese Journal of Physiology , 22(5), 51731. Retrieved fromhttp://www.ncbi.nlm.nih.gov/pubmed/4539646

Thyroid function and saturated fat