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Originally Posted by poke
Surprised by some of the negative responses. This is Peter the Hyperlipid guy we're talking about, not a Cheerios-eating standard-issue dietitian.
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Here, here! Peter is my go-to guy for actual science rather than speculation.
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I would like to have seen him talk a little about possible long-term thyroid down-regulation on ketogenic diets. I can't find all that much information on it, possibly because there isn't much apart from scattered anecdotal reports.
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There's actually a ton of it - in medical journals and books. Search for anything related to Peripheral Thyroid Hormone Disorder (unlike T4, T's 1, 2 & 3 are mostly manufactured in peripheral tissue like the liver and kidneys, and not in the thyroid gland itself) and bingo - there it is. It just hasn't made it into the mainstream media or conventional medical wisdom yet.
Long-term ketosis can (and did, for me) act in precisely the same way that starvation level calories act on the metabolism: shut it down. The specific route it takes is to convert T4 not into the metabolically active T3, but the metabolically inert Reverse T3. It does this by switching iodine molecules in a mirror image way. Result? Plenty of T4 gets made (thus showing a 'normal' thyroid function on tests, which is true since the *gland* is not affected), but not only do T3 levels plummet as Reverse T3 rises, the remaining T3 is blocked from entering the cells at the receptor level. One becomes, in effect, thyroid hormone resistant in the same way that one's cells can become insulin resistant. For reasons not yet known, this seems to happen mostly to women rather than men, and mostly to menopausal and post-menopausal women.
The prevention for this (and oh, how was Jan Kwasniewski was, to know this about 40 years ago) is to eat low carb, but at an increased level to keep you just out of ketosis -- about 50-70 carbs a day that includes glucose foods like potato and rice. Although I learned this too late to prevent myself from getting the disorder (eating 20 or fewer carbs a day for years), correcting my diet to include the higher carbs and specifically the glucose carbs from modest amounts of potatoes, rice and bread has helped. The weight re-gain has stopped, and fat burning has begun again.
The treatment is to do the same, but also to take pure T3 (Cytomel) until normal temperature is achieved once more and all hypo symptoms (like weight gain or the inability to lose any more weight far from, or close to goal) are gone. It will also correct one of the biggest symptoms of this problem (which was the one that got me to researching all this in the first place): inexplicable, outlier high Total Cholesterol levels. Although my HDL was very high (97) and my trig's very low (49-62), and my calcium and c-reactive protein levels were 50% of *low* risk -- my cholesterol climbed from 200 to 381 in eighteen months. It made no sense at all -- until I learned that the iodine molecule on the T3 enzyme signals the liver that cholesterol levels are fine -- and that the mirror image molecule in the Reverse T3 enzyme can NOT signal the liver -- that it all began to make sense to me. This is why medical texts advise treating high cholesterol caused by this condition not with statins -- but with thyroid medication.
This medication has two effects: the T3 suppresses the T4 we normally get from food, and thus signals to the thyroid that no more is needed. The Reverse T3 pool then dries up (having no source to feed it), and when completely gone the T3 cell receptors become unblocked, allowing the T3 (ingested, thus not needing to be converted from T4) to reach the cells once more. In effect, it's the same as doing what is required to make cells insulin sensitive again, and is as important to proper metabolic regulation.
I go for my first blood test since beginning T3 therapy a month ago on Thursday, and hope and expect to see if not a drop in TC, no further rise.
And oh yes -- I had to do the research, diagnosis and treatment protocol myself. My PCP didn't have a clue. Big surprise there.
Lisa