Do you have hypothyroidism? Are you wondering if you can do the ketogenic diet when you have hypothyroidism?
The short answer to this question is you can. The more long nuanced answer is the subject of this blog post. We will discuss:
- What labs to do if you have this concern.
- What things to consider if you are looking at this diet and have hypothyroid.
- What some of the research has to say about this question.
So if you want to know the details keep reading we will get into the details.
Can You do a Ketogenic Diet If You Have Hypothyroid?
The thing with the ketogenic diet and hypothyroid is that there is a theory or hypothesis that this diet will slow the conversion of your T4 into T3. To that you might say, why is that important?
Well T3 is the active form of your thyroid hormone. T4 is the main thyroid hormone that your thyroid gland makes. The T4 hormone does not really do a whole lot in terms of thyroid activity in your cells and tissues. However it is converted in the peripheral tissue, your cells and tissues all over your body, into T3. These levels of T4 and T3 can be measured in your blood. The theory is that following a ketogenic diet will cause less of this conversion into the active form of the thyroid hormone.
By the way, this T3 hormone is also responsible for the thermogenic and metabolic effects of your thyroid hormone. So if you are making less of this then potentially you will to be less metabolically active. Most of the people doing the ketogenic diet are doing so to lose weight, not everybody but most.
In that sense then maybe thyroid effects are negating some of that weight loss effect of ketogenic diet by reducing the conversion of your T4 to T3. Let's take a little deeper dive into this and look at what some other research actually says about it.
Research on Ketogenic Diet and Hypothyroid
One study looked at children that were put on a ketogenic diet to prevent seizures. These were epileptic children that medications were not working for to lower or prevent their seizures. Over the course of about one year the researchers found those on this diet had a statistically significant increase in the diagnosis of hypothyroidism. Specifically, about 17% of the children they followed were diagnosed with hypothyroidism.
Another smaller study looked at the same demographic and they found a trend towards decreased thyroid function. This study was over two years but they did not find a statistically significant increase in actual hypothyroidism. With that said, there was a small trend toward decreased thyroid function.
A few studies in adults looked at the same question. These did show a decrease in some of the thyroid measurements like a decline in some of the thyroid measurements. Specifically they saw a decrease in the conversion of T4 to T3. The actual T3 measurement was lower but there was no change in the T4 measurement. They didn't show any statistically significant change or impairment in things like metabolism or the overall thyroid function. There was also no increase in thyroid symptoms. So it wasn't clear overall that people were getting hypothyroidism. It was clear that there was a decrease in the overall T3.
So what could be going on here is a possible increase in cortisol. When doing ketogenic diets your glucose levels are lower and cortisol is secreted to increase release of stored glucose. This is what cortisol does. This increased cortisol could be taking some of the T4 and putting it into what is called reverse T3. That reverse T3 is no longer accessible to get converted into the T3. It's also possible that the body could just be more efficient and so there's less conversion going on because less T3 is needed. Those are two possible scenarios that could be going on when you are doing a ketogenic diet. So now you might be asking what does this mean for me? Can I do the ketogenic diet if I have hypothyroidism?
Bottom Line With Ketogenic Diet and Hypothyroid
You can do the ketogenic diet when you have hypothyroid. You should be aware that the conversion of T4 to T3 could go down. As such, if you do have hypothyroidism you should be a little more cautious in doing a ketogenic diet. You may want to get these tests done before you are already on the ketogenic diet. You should be measuring T4 and T3 and compare after you are on the diet and make sure it doesn't go too low. Usually when we measure this it is the free T3 . You can and should also measure the reverse T3 and look at cortisol.
If you are doing ketogenic diet and you have low thyroid function you should be measuring these tests before and after starting. If you are not having a whole lot of symptoms of low thyroid like weight gain, feeling cold, hair loss, fatigue, etc then maybe you don't have to worry about it as much.
These are some things to think about when you are doing ketogenic diet or considering ketogenic diet and you have hypothyroidism. If you have questions this content or about your thyroid function after starting a ketogenic diet leave it in the comments below.
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