High Reverse T3: 6 Causes + How to Avoid them

Why You should care About your Reverse T3 Level

If you are new to the world of thyroid problems then something like reverse T3 may be a bit of a conundrum to you. 

I know it may seem confusing but we can break it down into very simple terms which will help you understand why this metabolite is so important to your thyroid health (and therefore overall health)!

So what is reverse T3?

Reverse T3, sometimes referred to as rT3, is best thought of as an anti-thyroid metabolite. 

Meaning that it is something your body creates which is designed to slow down thyroid function. 

Why would your body need to slow down thyroid function?

There are actually many (good) reasons why your body might want to do this. 

Think about the case of being seriously ill. 

Does it make sense for your body to burn excess energy or does it make sense to put more energy into your immune system to help your body heal?

Your body can manipulate how much energy it is using (and where that energy is being utilized) through reverse T3. 

Okay, great, but how does your body make reverse T3? 

This is where things get interesting:

Reverse T3 is created from T4 (yes, the same T4 that is found in thyroid medications like Synthroid and levothyroxine). 

Your body will either turn T4 into the active thyroid hormone T3 or the inactive anti-thyroid metabolite reverse T3. 

And it chooses which to produce based on a NUMBER of very important factors

If your body chooses to make more reverse T3 than regular T3 you WILL feel symptomatic and you will feel the symptoms of hypothyroidism

Why?

Because that reverse T3 will BLOCK the action of T3. 

So even if your T3 levels are normal it doesn't matter because reverse T3 will block its effects. 

Hopefully, this is making sense!

And this is why you should REALLY care about your reverse T3 level

Because this reverse T3 level will likely directly correlate with how you are feeling. 

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Foods to Avoid if you have Thyroid Problems: 

I've found that these 10 foods cause the most problems for thyroid patients. Learn which foods you should absolutely be avoiding if you have thyroid disease of any type. 

How to Calculate "Optimal" Free T4, Free T3, & Reverse T3 Ratio: 

Calculating these ratios is important because it can help you determine if your efforts are on the right track and whether or not your medications are working. 

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6 Causes of High Reverse T3

There are many triggers that cause your body to start creating reverse T3 over T3. 

And it's important that you, as a thyroid patient, understand exactly what causes these things. 

Knowing and having this information will help you because you will be able to improve your thyroid by ensuring that you AVOID these things. 

If you can avoid them then you can improve your thyroid function by improving your T3 levels. 

I've explained in detail how to naturally improve your free T3 levels in this post which I would recommend you read as well. 

#1. Dieting and Calorie restriction. 

The first, and perhaps most common cause of high reverse T3, stems from calorie restriction and dieting. 

This one is so common because so many thyroid patients struggle with weight gain!

You may be in that category if you are reading this now. 

Having a sluggish thyroid (known as hypothyroidism) reduces your metabolism which leads to weight gain despite. 

Most thyroid patients then try to do what everyone does when they want to lose weight which is go on a diet. 

The only problem is that dieting causes DAMAGE to your thyroid by INCREASING your reverse T3 (1). 

The more you cut your calories the slower your metabolism will become and the more likely you will be to gain weight once you resume eating a normal amount. 

This entire process is mediated through reverse T3 levels. 

In fact, if you were to check your reverse T3 levels right after you get done with losing weight you will most likely find that it is sky-high. 

I've tested so many people after diets like the hCG diet and I can tell you that these diets are notorious for causing spikes in your reverse T3. 

But does your reverse T3 go down once you start eating normally again?

Not quickly (it can take years), and this is why so many people (about 99%) regain all of their weight. 

You can easily test your reverse T3 to see if you have this problem. 

How do you lose weight if you have a sluggish thyroid?

The first step is to BALANCE your thyroid hormones FIRST. 

Simply getting on the right type and dose of thyroid medication is enough to cause effortless weight loss. 

This weight loss will most likely not be complete (complete in the sense that you will get back to a normal weight) but it should be enough to help you lose 5-20 pounds without changing your diet. 

Once you get to this point you can focus on your other hormones, cleaning up your diet (NOT restricting calories), exercising, managing stress, taking supplements, and so on. 

You can find more about how I help thyroid patients lose weight by balancing their hormones in my weight loss guide

The moral of the story here?

If you've been on a diet recently where you either consciously or unconsciously restricted your calories then there is a good chance that you have accidentally damaged your thyroid. 

Make sure that you AVOID ALL diets which want you to restrict your calories for a prolonged period of time (3 weeks seems to be the cut off). 

And by restriction, I am talking about anything less than around 1,500 calories or so. 

If you eat, say, 1,200 calories per day for 4 weeks straight then there is a good chance that you will see a spike in your reverse T3 levels. 

#2. Inflammation. 

Next on the list is inflammation. 

Inflammation can be caused by a lot of different things so you may need to do some digging to figure out the cause in your case. 

Inflammation causes a spike in reverse T3 because it forces your body down the T4 to rT3 pathway (2). 

Both systemic (meaning all over your body) and cellular (meaning low-grade inflammation which is hard to test for) can cause this problem. 

Most people with inflammation know that they have inflammation. 

People with inflammation tend to feel fatigued, sore, achy, have joint pain, suffer from headaches, rashes, and so on. 

These non-specific symptoms often indicate that inflammation is present in your body. 

If you really want to confirm that inflammation is present you can order tests such as the ESR or CRP (these are blood tests which assess for inflammation). 

These tests don't pick up all forms of inflammation but they are a great starting point. 

natural thyroid supplements version 2

In my experience, most cases of inflammation are caused by the FOODS that you eat on a day to day basis. 

Foods high in sugar, processed foods, and foods made with industrial seed oils, are often the culprit. 

By cleaning up your diet you should be able to see a reduction in inflammation fairly rapidly. 

You can also take anti-inflammatory supplements to force down inflammation with things like fish oil

I use fish oil myself on a daily basis to help keep inflammation low. 

Another huge source of inflammation is from the gut (but we will focus on that separately below). 

#3. Nutrient Deficiencies. 

What about deficiencies in vitamins, nutrients, and minerals?

Yep, deficiencies in these important nutrients can absolutely contribute to high levels of reverse T3. 

But how does this happen?

These nutrients are used as CO-FACTORS to help certain enzymes function in your body. 

Remember when I talked about converting T4 into T3?

That conversion process is mediated by certain enzymes and co-factors and certain nutrients play an important role in helping that process go faster (or slower if you are deficient). 

So you can imagine a scenario in which you are deficient in the nutrients which help this process go. 

If you are, your body may WANT to convert T4 into T3 but may be unable to or may be doing it slower than it wants to. 

This leaves you with the opportunity to use certain supplements to help augment this process and FORCE conversion in your favor. 

There are several nutrients that play a role in thyroid function (in general), and you should absolutely be aware of all of them. 

I've written about these vitamins and why they are so critical to thyroid function here (make sure you read it if you haven't already because you can take supplements to improve your thyroid function). 

The nutrients that you should be aware of include Zinc, Selenium, Vitamin E, and Vitamin A. 

A deficiency in ANY of these nutrients may diminish how well your body can convert T4 into T3 and increase T4 to rT3 conversion. 

This is actually great news. 

Why?

Because taking supplements is something that you can relatively easily control and something that may help you. 

We know from studies that taking these nutrients actually helps as well!

For instance, this study (3) showed that taking Zinc did improve thyroid function in people who were Zinc deficient. 

And with soil depletion of nutrients and stress depleting certain nutrients (and just poor diet in general) these nutrient deficiencies are actually quite common. 

This is one of the reasons why I am so passionate about using supplements. 

I find they are a GREAT way to naturally improve thyroid function and health. 

If you are ready to start using supplements to improve your thyroid you can find my recommended products below:

Zinc and selenium tend to help more with T4 to T3 conversion while Vitamin A and Vitamin E tend to help more with thyroid cellular activity (and sensitivity). 

#4. Intestinal Dysfunction. 

Next, we have intestinal dysfunction. 

Don't let the name confuse you. 

Intestinal dysfunction refers to ANY problem of your gut in general. 

Usually, this occurs in the context of an imbalance in healthy and unhealthy bacteria in your gut. 

But it can also occur secondary to inflammation or damage to your gut lining (such as that seen in increased intestinal permeability or leaky gut). 

Both conditions result in the same thing: 

Increased reverse T3 levels. 

How or why does this occur?

Because approximately 20% of all thyroid conversion in your body occurs in your gut (4). 

Remember:

Your gut is a huge source of hormones, neurotransmitters, immune function, and thyroid conversion for the entire body. 

ANY inflammatory problem (or dysfunction) in this area can compromise any of these areas. 

For our discussion, we will focus mostly on thyroid function. 

You can imagine that if up to 20% of T4 to T3 conversion occurs in the gut that certain gut problems may limit that percentage and lead to higher reverse T3 levels. 

What you may not realize is that pretty much any issue in the gut can cause this problem. 

Irritable bowel syndrome, small intestinal bacterial overgrowth, acid reflux, yeast overgrowth (fungal overgrowth), gas, bloating, constipation, diarrhea, and so on. 

These are all 'canaries in the coal mine' so to speak and may reflect gut-related issues.

What's more, is that MANY thyroid patients have these problems by virtue of how thyroid hormone influences gut function!

So if you already have thyroid dysfunction (no thyroid, Hashimoto's, or hypothyroidism) then there is a good chance you are suffering from these gut issues. 

Treating or addressing these gut issues is paramount if you want to address your high reverse T3 levels. 

#5. Stress. 

Next up is stress. 

And here I am really talking about stress from any cause. 

I probably don't have to convince you that stress is a bad thing. 

We already know that stress can lead to weight gain (5), it can increase insulin resistance, it can lower testosterone levels, it can cause premature aging, etc. etc.

These are obviously things you don't want to have happened in your body. 

But we can also add to this list that stress increases your reverse T3 levels and negatively impacts your thyroid. 

It does this because it impacts your cortisol levels. 

Remember:

Cortisol is your stress hormone and it is secreted in times of stress on the body. 

The more stress you are under the higher your cortisol will be and the more it will impact your thyroid function. 

For this reason, it is imperative that you do your best to not only AVOID to eliminate as much stress as possible from your life!

If you can't eliminate sources of stress then you will need to take steps to improve how resilient your body is to this stress. 

You can do this by taking certain supplements such as adrenal adaptogens, using meditation or prayer, eating a healthy diet, supplementing with activated B vitamins and so on. 

If you want to know if stress is impacting your life then make sure you learn more about cortisol testing. 

You can test your cortisol levels fairly easily

#6. Lack of Sleep. 

Last on the list is a lack of sleep!

If you are not sleeping enough then this will DRIVE up your reverse T3 levels. 

What's the magic number here?

You should be looking at getting at LEAST 8 hours of QUALITY sleep each night. 

Some of you may actually need more than this (I fit into that category) and while some of you may feel 'fine' with less that doesn't mean that your body can actually handle fewer than 8 hours of sleep. 

So even if you feel 'fine' it doesn't mean that it isn't negatively affecting you in some way. 

If you have an elevated reverse T3 level and you are only sleeping 6 hours per night, for instance, then this might be the sole cause of your high reverse T3 (even if you are otherwise feeling normal). 

The number of hours you sleep is important but so is the quality. 

Make sure you are taking steps to sleep in a cool, quiet, dark environment each night which is free of interruption so that you can sleep soundly each night. 

This is VERY important as well. 

Do your best to avoid sleeping aids and sleeping supplements, as well, as these do not necessarily force your body into a restful sleep and in some instances may actually make sleep more difficult long-term. 

Your Next Steps? 

The bottom line?

If you are someone who is struggling with thyroid-related issues then one of the FIRST places you should look at is at your reverse T3 levels. 

High reverse T3 levels can explain why some people feel sluggish or hypothyroid despite taking thyroid medication and despite having otherwise 'normal' thyroid lab tests. 

I recommend getting a reverse T3 as part of my recommended thyroid lab panel (which is much more comprehensive than what your doctor would normally recommend). 

Getting this complete panel will help you put all of your labs into context and will help you understand what is happening with T4 to T3 conversion in your body. 

If you have a high reverse T3 level your next step is to try and determine the CAUSE. 

Use this list above to help you hone down that issue and then address the problem with the therapies I've listed above. 

Now I want to hear from you:

Do you have a high reverse T3 level?

Have you had your reverse T3 level tested before?

If no, are you going to get it tested?

If you do have a high reverse T3 level, what therapies have worked for you to help lower it?

Leave your questions or comments below to keep the conversation going! 

References (Click to Expand)

high reverse t3
Dr. Westin Childs

Dr. Westin Childs is a Doctor of Osteopathic Medicine. He provides well-researched actionable information about hormone-related disorders and formulates supplements to treat these disorders.He is trained in Internal Medicine, Functional Medicine, and Integrative Medicine. His focus is on managing thyroid disorders, weight loss resistance, and other sex hormone imbalances.You can read more about his own personal journey here.

2 thoughts on “High Reverse T3: 6 Causes + How to Avoid them”

  1. Dr Childs,

    You are the only physician in the content creation world that truly addresses RT3 and actually give actionable tools. Thanks to implementing two of your suggestions – #1 Candida treatment and #2 Adding Curcumin, my up and down RT3 has stabilized to low normal ranges.

    I have a request, my latest insulin test revealed low insulin 1.6, normal blood glucose 85. Would you do a post on LOW INSULIN and its impact and treatment?

    Reply

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