How Does Keto Affect Your Thyroid?

Published: April 26, 2019

How Does Keto Affect Your Thyroid

Before you think that the ketogenic diet’s going to completely disrupt your thyroid function, watch this video. Hey, I’m Thomas DeLauer with Keto-Mojo, and I’m going to give you the breakdown of what’s happening with your T3 levels, your T4 levels, and your overall thyroid function when you’re following the ketogenic diet. So first and foremost, a lot of the bad press simply comes from the fact that sometimes when you’re on a ketogenic diet, you can see a small decline in T3 levels. Now T3 is the active circulating thyroid hormone, but it is not a direct indicator of thyroid function itself.

Diabetes and Metabolism Journal Study

See let me explain some stuff. There’s a study that was published in the journal Diabetes and Metabolism, and it found that when people went on the ketogenic diet, that they had a big increase in fat substrates in their blood. They saw an increase in glycerol, they saw an increase in free fatty acids, they saw an increase in beta-hydroxybutyrate, and they saw a decrease in glucose and a decrease in insulin. But they also saw a decrease in T3, but their T4 levels remained unchanged. Let me explain what this means because this is the particular study that’s caused a lot of confusion for people. All that this means is that at that very point in time, the T3 levels were lower. If the T4 levels were low, then there may have been some cause for concern. You see, T4 is the precursor to T3. T4 converts into T3, and if T4 levels were super elevated or super declined, then we would be concerned. But since T4 levels didn’t change, it’s not that big of a deal because what that means is that the thyroid is still functioning, there’s just not a need for it to ramp up T3 production, so it’s really not concerning.

Metabolism, Clinical and Experimental Journal Study

See, lower T3 doesn’t always mean things are bad, and I’ll explain a little bit more about that in a second. But there’s another study, and this study was published in the journal Metabolism, Clinical and Experimental. It took a look at test subjects, in this case six weeks with 12 healthy men. 12 healthy men that had been accustomed to a traditional carbohydrate rich diet, about 48% carbohydrates, and then they had them go keto. When they had them go keto, they noticed some interesting results happened. They had a big decrease in fat mass and they lost about 3.4 kilograms of fat on average and they gained approximately 1.1 kilogram of muscle. This is really powerful. They had a small increase in T4, they had a reduction in insulin and glucose, and their T3 levels ultimately remained unchanged. So they had a small increase in T4, they had a small increase in thyroid production, which is pretty interesting, but just not an increase in overall thyroid hormone at that point in time. The reason that this is so unbelievably fascinating is because they lost weight, but they also built muscle, which if you are hypothyroid, and your thyroid wasn’t working, this would be very, very difficult to do. It’s very difficult to burn fat and build muscle if your thyroid isn’t functioning. Even though T3 levels remained unchanged, and a small elevation in T4, everything still worked fine.

Here we have two studies, the Diabetes and Metabolism, and then the other study I just referenced, they kind of have conflicting information. The point is a lot of it depends on the time in which T3 is tested. So let’s go ahead and talk about why T3 levels might get suppressed on keto. It all has to do with calorie restriction. See it doesn’t matter whether you’re doing keto or not, if you’re suppressing calories, you’re going to suppress your T3 levels. You see, your thyroid is sort of like the barometer for your body. It’s going to always kind of balance with what’s going on. If your metabolism is slowing down because you’re reducing calories, then of course your T3’s going to slow down, it doesn’t need to stay ramped up. You’re a lesser-weighing person, you’re eating less, less metabolism overall, less thyroid. It’s plain and simple.

Understanding T3 Levels

A lot of times when people go on a keto diet, they’re restricting their calories too because they’re trying to lose weight. So of course your T3 levels are going to be compromised, but you have an added benefit. You retain a lot of muscle when you’re on a ketogenic diet, actually your T3 levels are going to be less suppressed on a keto diet than they would be on a traditional calorie restricted diet. Just to put this into context, there was a study that was published in the journal Thyroid that took a look at 47 test subjects, and they measured them over the course of 12 months while they were losing weight. On average, they lost between five and 10% of their overall body weight. At the end of that 12 months, they found that there was a change in their T3 levels. It went from 112 nanograms per deciliter down to 101 nanograms per deciliter. It’s a pretty dramatic decrease, and this was on a wide spectrum of just weight loss protocols, not just one. They just had them reduce calories and lose weight, and they all ended up having a pretty even drop in T3 levels. So it’s nothing to be concerned with, but if your T3 levels are low, there actually are some positive effects. The JAMA published a study that found that when your T3 levels are lower, you actually live longer. You see, your metabolism in essence isn’t having as much waste so it’s easier to live longer.

Relationship Between Calorie Restriction and Longevity

Calorie restriction has shown to improve longevity in a lot of different animal models and human models. But what’s really cool is that when we look at the T3 link, there is some direct correlation. The study published in JAMA found that generally speaking, when thyroid was lower, subjects lived three and a half years longer. But I have to add one more thing. There’s a lot of misconception out there surrounding the world of carbs and thyroid. People say that when you consume carbs, it elevates your thyroid hormone, it improves your thyroid function, which is not really the case. What happens is glucose metabolism in and of itself requires T3.

So yes, when you consume carbs, your T3’s going to go up. But guess what, it’s not going up for your entire body. It’s only going up to facilitate the metabolism and the process of said glucose. Let’s say for example, you consume 100 grams of carbs, your body’s going to elevate just enough T3 to process those carbs and nothing above and beyond. So sure, you might have an elevation in T3, but it’s only there to process the carbs, not to actually boost your metabolism. I rest my case, right then and there. Anyhow, don’t be afraid of keto and your thyroid. If anything, it’s actually going to allow a nice level of homeostasis to begin occurring as far as your endocrine system’s concerned. Make sure you’re keeping it locked in here with Keto-Mojo and leave the guesswork out of the equation. When it comes to testing your ketones, rely on the Keto-Mojo meter, so you can get an accurate and thorough reading every single time. I’ll see you in the next video.


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