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Thyroid UK
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Deiodising mechanism

When I switched to a ketogenic diet my need for NDT dropped significantly - I went from 2.25 tablets to 1.25. For the first 8 months or so I stuck to 20-25grams of carbohydrate daily. That's not a lot, and significantly limits variety in the diet. So I bought myself a ketone meter and started to experiment with higher levels of carbohdrates. I found I could eat about double the original amount as long as I kept away from sugar and high carb foods like rice and potato.

I didn't notice that I was becoming more fatigued, and my weight even crept up a little bit. Its taken over 3 months for me to realise that my T3 levels must have dropped! I increased my NDT the last 3 days and feel heaps better!

So, I want to understand the whole process of T4 to T3 conversion better. I've found references to the diet improving conversion in people on medication. But what is the role of blood glucose? and/or ketone levels?

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I have no idea, sorry! Chris Kresser is pro-paleo, & writes a lot on gut health, thyroid, autoimmune, & general health. Try taking a look at his website for links that might help you find out what you want to know.

my.chriskresser.com/ebook/t...

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No, not really. Because he is arguing that you need glucose and T3, but as far as I can tell increasing my glucose intake(and it was very gradual!) has reduced conversion(or maybe utilisation, I can't test all the time!). So I have less T3 and the glucose amount becomes irrelevant. The moment I increased T3 (by increasing NDT) I felt better. But I did not increase my glucose intake, in fact I reduced it a bit.

I also doubt his argument because by and large ketones replace glucose in all the burning processes. There is some glucose needed by certain brain functions, and that is generated by the liver from protein in the absence of glucose. If glucose were essential for energy all those long term keto eaters would be dead by now.

Furthermore, although I haven't measured my cortisol levels my adrenals are coping far better on keto than before, when I was well medicated according to the tests, but still had some hypo symptoms. I sleep better, am far less anxious, and recover far quicker from stressful events.

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OK

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Ruthi, I've just looked up what you were saying about ketones burning in terms of Krebb's cycle. I got to it through Wikipedia. Acetyl-CoA is the 'food' input to the cycle. This can be derived from glucose, or two different routes if you don't have glucose, ketones outside the cell and fatty acids I think inside the cell.

The argument as I understand it for why this leads to weight loss is that the route is more 'inefficient', effectively you're spending more energy to get the energy you get.

All the stuff about glucose storage in this article doesn't necessarily apply, because you're using proteins and fats to fuel Krebb's cycle.

This seems to be a very interesting split in hypo people. There are often posts about people really benefiting from low carb diets, but there is this argument out there that low carb is bad for hypos. I had a fairly bad experience on it myself, and now eat lower carb than I did before. I find I need things like fruit and the occasional rice/pasta/potato, otherwise I am prone to hypoglycemia just as this article describes.

It makes me suspect that we all have impairments at different locations in the process, in the same way that we have different sets of symptoms.

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Oh absolutely, and my reading has so far turned up the fact that there are actually three deiodinase enzymes helpfully named D1, D2 D3!! So that is three possible routes to conversion before we start looking at the way T3 works once generated.

I'm probably just going to have to go with what makes me feel my best. Its a pain, because I would very much like to eat more fruit. Never mind!

I worry too a bit because the general advice is to supplement with salt (I do, and its critical to prevent headaches for me), potassium (which I do in a rather desultory way because my diet is fairly rich in potassium anyway), and finally magnesium. Magnesium in all forms stops me sleeping, so I have stopped taking it.

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Very interesting. It alarms me a bit to think we need to learn about all this biochemistry.

I think the issue of transporting T3 into cells is going to be important for me, and I'm roughly aware there are two transport mechanisms, alpha and beta, but from there the papers are he-a-vy.

With your question, and GG's comment, there's the deiodinase conversion process, and the sugar metabolism/respiration reaction to worry about, too, as big phases in the process.

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Thanks GG, great article!

For anyone who hasn't clicked through, this is about a process downstream from of deiodinase, it's about bringing T3, glucose and oxygen together in the cell to make energy. The article talks about how the processes used to get the glucose where it needs to be. Overall it is both positive about low carb diets.

The thing I came away thinking is that I really need to read up on ATP. I believe this is Krebb's cycle, I vaguely remember it from school. I remember it needs ATP, carbohydrates and oxygen at the start, and pushes out a larger amount of ATP, and carbon dioxide and maybe water at the end. This is why we breath in oxygen and breath out carbon dioxide. Then ATP is what the cell uses as fuel.

I don't remember thyroid hormone mentioned in any of the school version of this, but it does sound like what I understand T3 to be.

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You're welcome. :)

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The brain uses blood sugars to make keytones. As we age this decreases. Using a Ketogenic Diet helps.

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Very interested in your journey to keto - I'm trying to get my head round counting the carbs! Which keto meter did you get?

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I'd be interested in finding out about which ketone meter you bought too. Thanks

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I'm needle phobic, so I bought a Ketonix breath meter. There seems to be a few reliability issues, but mine works fine. However, if you are OK with needles then an Optium Neo blood monitor will measure both blood glucose and blood ketones although the ketone strips are about £1 each! There are people out there using breathalysers, but they also don't seem to last, and there are issues of calibration.

The Ketonix actually measures acetone in the breath. It is only accurate if you eat pretty low carb and don't drink, but it worked well enough for me to establish how high I can go without bumping myself out of ketosis. I wasn't too worried about actual numbers. As it happens its now fairly irrelevant, since I have learned that I feel better the lower my carb intake, even if I feel deprived of all those carby 'treats'.

The ketogenic diet doesn't work via inefficient energy burning by the way. It works largely by normalising appetite - whereas high carb intake causes wild fluctuations in insulin and hence blood glucose, and when BG drops, that sugar hunger kicks in very quickly. Whereas carb burners can run out of glucose stores completely, we always have a plentiful supply of fat on board, even when we are very lean. If you run a super-marathon you can burn 30-40,000 calories in a day from fat stores, without eating. You'll need to replenish your fat stores, of course, but not top them up then and there to continue to function.

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