Blood Sugar

Intermittent Fasting and Thyroid Problems: Cause for Concern?

by Mike Mutzel




This video may help clarify a few concerns people have about fasting and thyroid function, especially:

-Weight loss does decrease T3 (this is common, expected)
-Low calorie diets in general reduce thyroid hormone levels (T3)
-Why prolonged fasting decreases free T3 and increases reverse T3 (it’s a means to spare muscle from being catabolized)
-Where the idea that “50 grams of carbs” are needed for optimal thyroid function
-Short term VS long-term fasting and thyroid function

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 a reciprocal 58% increase in rT3


Key Research Articles Mentioned Herein:

Rosenbaum, M., & Leibel, R. L. (2010). Adaptive thermogenesis in humans. International Journal of Obesity, 34(S1), S47–S55.

Serog, P., Apfelbaum, M., Autissier, N., Baigts, F., Brigant, L., & Ktorza, A. (1982). Effects of slimming and composition of diets on VO2 and thyroid hormones in healthy subjects. The American Journal of Clinical Nutrition, 35(1), 24–35.

Azizi, F. (1978). Effect of dietary composition on fasting-induced changes in serum thyroid hormones and thyrotropin. Metabolism, 27(8), 935–942.

Spaulding, S. W., Chopra, I. J., Sherwin, R. S., & Lyall, S. S. (1976). Effect of caloric restriction and dietary composition of serum T3 and reverse T3 in man. The Journal of Clinical Endocrinology & Metabolism, 42(1), 197–200.

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  1. I fasted 17 days at Health Oasis in Thailand in June 2012. Started at 5’4″ 107 lbs, left at 92 lb, barely able to stand. I thought it odd that no mirrors existed; I would have seen my bare bones status. I returned to USA July 2012 ill, nutritionally deplete, adrenal exhausted, hypothyroid. I was diagnosed Chronic Fatigue,CFS, in 2014 Dec. I experienced severe hypoglycemia, was diagnosed pre-diabetic. CFS effected inability to exercise, barely able to work, inability to think clearly, no mental or physical stamina. I was exhausted, unable to stand due to dizzy spells in 15 min. I continue to still struggle with CFS mediated with EMF scalar protection, C60, MTC oil, VOXX patches, B12 patches, iodine supplement. I take CBD oil and melatonin to sleep, glutathione whenever I attempt to walk or swim no more than 20 min, BCAA post exercise. Im doing Biotherapeutic Drainage, once every two months I do intravenous chelation to reduce high arsenic, lead, and mercury. Is there anything else I can do? How to subscribe to channel on Tuesday? I’ve no facebook. Eliminated it.

  2. Great video and content as per usual Mike thanks to you and Sam.

    One suggestion for next time, if possible have a mic for Sam, it would be helpful to viewers to hear the questions and comments he is reading from the live stream

    Thanks and look forward to the next one

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