Ketogenic Diets, Cortisol and Thyroids

If you've followed this blog for a while, you'll know that I already have a problem with the "diagnosis" of low functioning thyroid, but that I also suspected I had it for a while. I treated it and the symptoms improved. Hooray!

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If you know me in real life you'll know that almost the whole of this last month has been written off as one giant headache. That's not a euphemism, I have actually had a 'migraine' that has lasted weeks, with a really high fever and doctors diagnosing everything from kidney infection, fluid in my lungs, respiratory infection, glandular fever (newsflash: I'm immune to that), then an overactive thyroid was suggested (due to swelling) and now an 'extremely low functioning thyroid' (due to blood tests).

Well, it's not that surprising. My body is incredibly stressed, of course it's going to be in an adrenal dominant state! Because it's so low I've agreed to start thyroxine temporarily whilst we run some more tests and I get the exact numbers so we can work out the problem.

In the meantime, I wanted to talk a bit about some myths surrounding these issues and the ketogenic diet; largely because I think when we accept them, we stop looking for the cause of the problem, and that means we'll never fix the problem, only manage symptoms.

Myth 1: The ketogenic diet is stressful for the body

This myth comes from a misunderstanding about cortisol. Cortisol is our body's 'stress hormone'. Most arguments for ketosis being stressful stem from the idea that gluconeogenesis (how your body makes the glucose it needs if you don't eat a lot of carbs) require cortisol. 

The reasoning goes like this:
On a ketogenic diet, because you get very little glucose from the carbohydrates in your diet, your body manufactures it's own through gluconeogenesis (so far so good). Gluconeogenesis requires elevated cortisol (that is not true - we'll come back to it though). Too much cortisol damages your body (not exactly true either - cortisol is your body's intelligent, protective, response to something damaging, but actually as it's not true that it's raised for gluconeogenesis it's a redundant point anyway).

When your blood sugar begins to get low, glucagon (the hormone responsible for ensuring adequate blood sugar) promotes gluconeogensis and prevents the blood sugar getting low enough to trigger cortisol production.

If the blood sugar get's below 55mg/dl (your glucagon should have kicked in at 65mg/dl) the you experience hypoglycaemia - with anxiety, palpitations, sweating, tremors, dizziness, tingling, blurred vision, difficulty thinking... so if you aren't experiencing these kind of symptoms, cortisol isn't regulating your blood sugar yet. These symptoms are rare for most people on a ketogenic diet, so it's reasonable to conclude that the diet is not affecting their cortisol levels.

If you are concerned about your blood sugar you should check in with your doctor, regardless of what diet you follow, and you can buy a cheap glucometer, which would allow you to alleviate any concerns. If your blood sugar is low, you may need to experiment with eating more proteins.

This quote from explains it better than I can:

"On a keto diet, your body makes the modest amount of glucose it needs out of protein in a process called gluconeogenesis (GNG). There is a widely-held misconception that for GNG to occur, there must be high levels of the stress hormone cortisol in the blood. This mistake comes out of the fact that cortisol stimulates GNG. Therefore, it is reasoned, whenever you rely on GNG, your body has to produce and circulate more cortisol. This, however, is like arguing that since a reliable way to make people laugh is to tickle them, that every time you hear someone laughing it means they are being tickled. It turns out there are other ways to make people laugh, and there are other hormones that induce GNG"  

Myth 2: Ketogenic diets are bad for your thyroid

This myth is spouted so often that you'd assume there was some research behind it, but the only thing close to evidence is the fact that T3 hormone is lowered in those on a ketogenic diet and to be fair, low T3 in someone on a high carbohydrate diet only seems to happen in cases of severe illness. When you are in a period of rapid weight loss, starvation, or protein deficiency lower T3 is an adaptive, intelligent response from the body to prevent lean muscle mass loss

In other words, the more ketogenic our weight loss is, the healthier it will be because we won't be losing muscle mass with it.

Low T3 hormone is also associated with longevity, and a decrease in ketogenic dieters might actual be a sign of their lifespan increasing. Those who are very long-lived tend to have low T3 levels and it's not just because they are old. Genetic research into longevity confirms that low T3 is a good indicator of increased lifespan.

So yes, ketogenic diets affect your thyroid, but no, I wouldn't say that it was a bad thing. 

Now, I'm off to get more blood drawn to find out if my thyroid is actually under functioning, or whether I'm just adapting to an increased life span, but either way, the search for my mystery illness continues!


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