Why Bodybuilders Take T3 Thyroid Hormone

Why Bodybuilders Take T3 Thyroid Hormone

Believe it or not, there’s a fair amount of information we can learn from bodybuilders, especially when it comes to hormone management. 

I’m not suggesting or even recommending that you follow their advice, but there’s no question that this community serves as a reservoir of knowledge because they are essentially using themselves as human guinea pigs (1). 

case study of a bodybuilder using T3 thyroid hormone suffering from tachycardia

This leads us to the topic of the use of T3 thyroid hormone by the body-building community. 

Have you ever wondered why some people are able to lose weight rapidly while maintaining a muscular physique?

Or how movie stars are able to slim down or bulk up within a matter of weeks to months to get ready for their role? 

Contrary to popular belief, they do not possess insider secrets or special knowledge that isn’t available to the likes of you and me. 

No, the answer is all in the hormones. 

The unrestricted use of testosterone, growth hormone, insulin, and thyroid hormone certainly plays a role in many (but not all) of the physiques that you see on television and social media. 

But is this standard healthy? 

Should hormones be used to augment physiques and assist with weight loss? 

And what sort of takeaways can you learn from their use? 

That’s exactly what we are going to be discussing today. 

If you want to learn more about the use of T3 and how it has the potential to help with weight loss then keep on reading. 


Foods to Avoid if you Have Thyroid Problems:

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The Complete List of Thyroid Lab tests:

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T3 Thyroid Hormone & Weight Loss

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The relationship between thyroid hormones and weight is a lot more complicated than it might seem (2). 

It’s well known that low thyroid function leads to weight gain but it’s also widely appreciated that replacing lost thyroid hormone typically doesn’t lead to weight loss

At first glance, this appears counterintuitive. 

How can it be that the treatment for something that results in weight gain not result in weight loss, if the problem is corrected?

There are lots of potential explanations for why this occurs including the fact that many thyroid patients remain underdosed despite taking prescription thyroid medications and that weight gain in hypothyroid states is primarily fluid related (3) but let’s leave those aside for now. 

The topic I want to focus on here is the choice of thyroid hormone replacement that doctors use for hypothyroid patients. 

Almost without exception, thyroid patients are treated with thyroid medication that contains only T4 thyroid hormone (not T3, which is the topic of our discussion today). 

T4 thyroid hormone, while still a biologically active hormone, is nowhere near as active as T3. 

It’s hard to know exactly how much more powerful T3 is compared to T4 but it’s estimated to be anywhere from 4x more powerful to 200x more powerful (4) depending on which metric you look at. 

t3 thyroid hormone is considered to be much more biologically active compared to t4

The difference in biological activity almost certainly plays a role in why thyroid patients don’t lose weight when taking prescription thyroid medication. 

Why? Because they are using a very inactive and weak form of thyroid hormone. 

You would be hard-pressed to find articles or information about the use of levothyroxine and weight loss in the bodybuilding community for one big reason:

It won’t work. 

But the use of T3 thyroid hormone by itself, that’s another story. 

Because it represents the most powerful thyroid hormone, and because many bodybuilders are willing to put their health on the line to gain even a small advantage, the use of T3 is fairly common. 

How is it used? Primarily as a temporary solution to assist with weight loss when cutting fat mass. 

When taken in high doses, T3 thyroid hormone will increase metabolism, increase heat production, increase heart rate (5), and rev up the entire body. 

The result? More calories burned at baseline which means more weight loss for less effort. 

This may sound like a good deal and it may even be appealing to thyroid patients reading this, but it’s not without potential consequences. 

T3, Muscle Loss, Bone Loss, and Heart Enlargement

One big potential problem with the use of T3 is that it’s considered to be catabolic. 

Catabolism is a term used to describe the breakdown of a tissue in the body (6) and that’s exactly what the use of T3 has the potential to do. 

the difference in catabolism and anabolism

We will talk about the difference between healthy use and abuse in a second but what you need to understand here is that abusing T3 thyroid hormone may result in the breakdown of certain tissues including the bone and muscles. 

Muscle catabolism is obviously something that you can’t tolerate as a bodybuilder (the entire goal of bodybuilding is to build muscle, not lose it!) so this particular side effect must be monitored closely. 

In addition to its effects on muscles, T3 also has the potential to break down bone tissue (7). 

This problem with the breakdown of bone tissue is well-known in the thyroid community and is the very reason why your doctor will recommend against using T3 if you already have osteoporosis or low bone density in general. 

T3 use also has the potential to cause heart enlargement (8) which may increase your risk of atrial fibrillation but this is not due to its catabolic nature. 

Instead, heart conditions tend to be related to the increased demand put on the heart by the use of T3. 

Fortunately, these negative side effects only occur in certain situations including: 

  • The abuse of T3 thyroid hormone – In other words, using T3 thyroid hormone if you don’t need it or at doses higher than what the body would produce naturally. 
  • Using T3 thyroid hormone for extended periods of time – These side effects typically won’t be seen unless you’ve misused or abused T3 for many months or years. 
  • Using T3 thyroid hormone with underlying or existing medical conditions – You’re much more likely to develop bone problems, for instance, if you already had weak bone density prior to taking T3. 

While these side effects can occur in both bodybuilders (those with normal thyroid function) and thyroid patients (those with low thyroid function) alike, there is definitely a way to use T3 correctly (in those that need it) in such a way that mitigates or reduces the risk that you will experience any of these side effects. 

Let’s talk about that now: 

Takeaways for Thyroid Patients

The big takeaway for thyroid patients here is that there is a huge difference between the necessity of a hormone or a medication and the abuse of that hormone. 

In the case of T3 for thyroid patients, there is a medical necessity. 

In the case of a bodybuilder using T3 thyroid hormone, this could be considered abuse or misuse. 

The reason? 

One person needs it to function because they can no longer produce it naturally and the other is using it to take advantage of supraphysiological side effects. 

I’m not casting judgment on anyone who uses T3 for their own personal gain, that decision is up to them, but we need to be careful not to conflate these two situations and lump them together. 

For instance, it’s not fair to suggest that T3 will cause the same side effects in thyroid patients as it will in bodybuilders because, even though the dosing may be the same, the total level of thyroid hormone in the body is much less for those with thyroid dysfunction. 

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I’ve long been a proponent of T3 thyroid hormone use in thyroid patients because most thyroid patients aren’t able to create enough of it through the thyroid conversion process

If you are taking a T4-only thyroid medication like levothyroxine then your primary source of T3 production comes from thyroid conversion. 

In the healthy state, the body naturally produces about 20% of T3 from the thyroid gland directly (9) and the other 80% comes from peripheral tissues. 

If you replace all of that lost thyroid hormone with only T4, you’re setting yourself up for low T3 and low T3-related symptoms (which is the situation that many thyroid patients find themselves in). 

In summary, the use of T3 thyroid hormone is a great option for a thyroid medication that can either be used by itself or in conjunction with T4 and T2

Whether or not it will cause side effects is not based on the medication itself but on the dose being used and the situation of the person using it. 

If you are someone who has normal thyroid function and you are taking a high dose to assist with weight loss then you better believe your risk of side effects will be high. 

If you are someone with low thyroid function and you are taking a physiologic dose to help bring your thyroid back into normal function then your risk of side effects is very small to nonexistent. 

Body Build Dosing vs Healthy Dosing for Thyroid Patients

In the bodybuilding community, the recommended dose of T3 is somewhere between 25mcg to 50mcg taken each day while cutting or losing weight. 

And, believe it or not, that’s not far off from the recommended dose that thyroid patients tend to benefit from based on my own experience. 

The difference between a bodybuilder using T3 and a thyroid patient using T3 is much different, though, for a couple of reasons: 

The first is that thyroid patients already have depressed thyroid function. 

In other words, they aren’t producing enough T3, to begin with. 

So even if they take the same dose as a bodybuilder, they won’t experience the same set of symptoms or side effects because they have less native thyroid function compared to the bodybuilder. 

Think of it like this: 

Imagine the healthy thyroid gland produces 80 mcg of T4 and 20 mcg of T3 each day. 

A typical thyroid patient may only be able to produce 60% of this value given that they have thyroid dysfunction. 

In this case, they would produce 48 mcg of T4 and 12 mcg of T3. 

The bodybuilder, on the other hand, would be capable of producing the regular amount. 

If you were to then add on the 25 to 50mcg of T3 on top of existing thyroid function, the bodybuilder would be at a much higher total level compared to the hypothyroid patient. 

So even though they are taking the same dose, the total thyroid hormone in circulation would be less in the case of the hypothyroid patient which means fewer side effects overall. 

And second reason, the use of T3 in the case of the hypothyroid patient may be medically necessary to improve quality of life. 

Let’s put it this way:

Would you be willing to take a medication that meant that you could more easily reach your target weight, have the energy to live your life, and reduce symptoms like hair loss or fatigue if it meant accepting a small risk of potential side effects at a later date? 

I’m not saying that T3 always causes negative side effects for thyroid patients, in fact, it’s usually the case that it doesn’t. 

But even if it did, would it be worth it to you?

Because this is the question that you really need to ask yourself. 

Are you willing to take a small potential risk in return for a better quality of life? 

The answer depends on you and your values. 

In the case of the bodybuilder, they are doing it because they value the results more than they value the potential risks, but the decision for a thyroid patient is a little bit different and should be treated that way. 

My Recommendation? Only Use T3 If You Need it (Don’t Abuse it)

Should you use T3 as a thyroid patient? Only if you need it. 

And whether or not you need it can be assessed by looking at a combination of your thyroid lab tests, the assessment of your conversion ability, and your symptoms

My experience suggests that lower doses of T3 in the range of 5 mcg to 25 mcg per day are not only well tolerated by thyroid patients but also very beneficial to symptomatic control. 

I would strongly recommend that you not misuse or abuse T3 because of the potential side effects its use may impart. 

If you are planning on using it in this way then make sure you aren’t using it for an extended period of time (no more than 6-8 weeks) to reduce the chance of negative consequences on bone, heart, and muscular tissues. 


There’s no such thing as a free lunch in economics and there’s no such thing as the use of hormones in the body without some side effect. 

Hormones, especially thyroid hormones, are among the most powerful compounds in nature (10) and their use should be limited to those who need them. 

Now I want to hear from you:

Were you aware that T3 is commonly used to assist with weight loss in the body-building community?

Are you personally taking T3 thyroid hormone right now?

Are you planning on taking T3 to better manage your thyroid? 

Leave your questions or comments below! 

Scientific References

#1. ncbi.nlm.nih.gov/pmc/articles/PMC7035845/

#2. ncbi.nlm.nih.gov/pmc/articles/PMC6711558/

#3. eje.bioscientifica.com/view/journals/eje/176/1/R15.xml

#4. ncbi.nlm.nih.gov/books/NBK285568/

#5. pubmed.ncbi.nlm.nih.gov/24692351/

#6. ncbi.nlm.nih.gov/pmc/articles/PMC7545035/

#7. ncbi.nlm.nih.gov/pmc/articles/PMC7230461/

#8. ncbi.nlm.nih.gov/pmc/articles/PMC5512680/

#9. ncbi.nlm.nih.gov/books/NBK499850/

#10. ncbi.nlm.nih.gov/books/NBK538498/

what thyroid patients can learn from bodybuilders that use t3 for weight loss

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About Dr. Westin Childs

Hey! I'm Westin Childs D.O. (former Osteopathic Physician). I don't practice medicine anymore and instead specialize in helping people like YOU who have thyroid problems, hormone imbalances, and weight loss resistance. I love to write and share what I've learned over the years. I also happen to formulate the best supplements on the market (well, at least in my opinion!) and I'm proud to say that over 80,000+ people have used them over the last 7 years. You can read more about my own personal health journey and why I am so passionate about what I do.

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63 thoughts on “Why Bodybuilders Take T3 Thyroid Hormone”

  1. Hello Dr. Childs,
    I am almost 66 yrs old. In my late 20’s, half my thyroid was removed due to a large nodule. Pathology showed Hashitmoto’s. I was on Synthroid for many years at 150 dosage.
    In my 30’s, I switched to generic Levo due to increases in cost of Synthroid. I do not think it saved me anything over the years as my TSH #’s fluctuate which caused a need for more lab tests.
    I now get a compounded Levo in rice powder as an inactive ingredient was making me have swollen eyelids daily. Now on 125 dosage and latest TSH test was at 44.4!
    I have been on this Journey for almost 40 years. I have a routine to take my pill daily. DR had me try 5 dosage of Liothyronine recently. After 11 days, my heart started fluttering. I stopped new med & contacted DR. Starting today, I am supposed to cut pills in 1/2 to take daily at 2.5 dosage. I am keeping an open mind but not thinking this is going to fix my problem.
    What is the best time of day to take the T3 med?
    Also, if the pills crumble during cutting, can I mix with water to dissolve and split the liquid into 2 doses?
    I am assuming with the short 1/2 life it would not work to take a 5 dosage every other day?
    Thank you for the help you provide to those of us in need,

    • Hi Deborah,

      I personally believe that taking T3 at night is the best option for most people, provided it doesn’t keep you awake.

      • I have some gum infection in teeth I have read there is thyroid connections would you fill me in on what you know about this. Thank you Dr. Westin
        My age is 72

      • I am hypothyroid and take a very small dose of armour thyroid every morning. I need to lose 20 pounds, that will not budge. Can I try T3 without labs?

        • Hi Lisa,

          It would not be a good idea to make adjustments to your thyroid medication dose without testing. It’s always possible that you could get it right with a blind guess, but it’s not advisable.

        • Lisa – I am in the same position as you are! I was diagnosed as hypothyroid in January and started with Levothyroxine. At my request the doc switched me to Armour thyroid (which includes both T3 and T4). I still do not ‘feel’ right but am trying unsuccessfully to lost 20 pounds. Very frustrated!

  2. Hi Dr Childs,

    I really appreciate all of your articles about Cytomel it has given me a lot of good information. After giving birth to my first child I became extremely hyper thyroid and had a thyroid uptake of 99% I ended up getting radioactive iodine therapy. For better or worse I obviously did become hypothyroid and since that time it has been a huge struggle for me to find the right medication. I am now on my third doctor and finally I was able to find someone who would put me on T3 only and it has been the best results that I have seen. I’m currently on 25 mcg of Cytomel and I think that I should go up another 5. I still struggle with fatigue and I haven’t lost any weight and I haven’t had any negative side effects at all. Do you think that it is necessary to take T4 in addition to T3 or if I am tolerating the T3 well can I just take it alone? Considering the huge benefit to my quality of life I would be comfortable taking this as long as my body will tolerate it I am 35 years old. Do you think that it could be a good long-term solution?


    • Hi Paige,

      I’ve seen some studies showing that long-term use of isolated T3 is safe but I personally don’t like keeping patients on it long-term. I don’t have any reason for that other than my gut instinct. My wife was on T3 for a long time but we spent the time to wean her off of it because we felt that was better for her health long-term. I definitely think T3 is worth it in the short-term but I’m not sure about the long-term (5-10+ years).

      • I’m on T3 only, 65 mcg/day on 3 doses, no fatigue no depression better cognitive and memory, lost a bit weight and only at little over weight, don’t know yet how it affects osteoporosis

        Before T4 for 25 years with extreme fatigue depression and bad memory cognitive, osteoporosis and ongoing weight gain

        • Hi Anette,

          That level of T3 is very likely to have a physiological impact on bone turnover. If you are still having residual symptoms with a dose of 65mcg then there are probably other non-thyroid issues that need to be addressed.

  3. I am taking 20 mcg of T3 every morning on an empty stomach and 100 T4 every night together with 100 mcg selenium, 10 of zinc, a bit of L-tirosine and a very small amount of iodine. All prescribed by a doctor. This routine has helped me A LOT with my symptoms. I am almost symptom-free now (for years). With the use of T3 the first thing I noticed was the reduction of brain fog and that I could lose weight for the first time in years (before I could not lose any weight even with strict diets) but I have also noticed, that the body somehow gets used to the supply of T3 and needs more to reach the same effect…and I don’t want to be increasing dosage, it’s dangerous!

    • Hi Teresa,

      The need for higher doses may also be indicative of other problems or changes in other hormone levels.

  4. Hello! I’m in levo and my dosage changes every 6 weeks based on dr requiring me to get my numbers checked. Anyway about 10 months ago she added t3 to the dosa 2x daily at 5mg. It it good to stay on T3 long term? My t3 numbers fall
    right in the middle of the range every 6 weeks. I also just purchased your t2 so I’m trying to figure out how to incorporate the pill with my other thyriod meds. Thanks

    • Hi Paula,

      Side effects associated with thyroid medication use are dosed-related. As long as you are not taking an excessively high dose, there are very little to no long-term consequences.

  5. Hi Dr.Child’s, my daughter is 20 , diagnosed hypothyroid 5 months ago and takes 25 mcg Tirosint 4 days a week and 50 mcg 3 days a week, she definitely has more energy taking this med , her tsh was recently 2.4, free t4 was 1.2 and her total t3 was 101 , what are your thoughts on adding cytomel? Her Ferratin was awful, it was 21 , she takes an iron supplement also, and thank you so much for all your information

    • Hi Lynette,

      I can’t give medical advice but many thyroid patients do very well on the combination of Tirosint plus Cytomel.

  6. What do you recommend for someone who has been on T3 for 7 years and has hashimotos? How would you suggest they start to wean off of it? What if hypothyroid symptoms return with the wean off the T3?

  7. Hi Dr C, love what you provide.
    I am 65 yrs old and for the past 2 years my ND has been trying to optimize my hypothyroidism with medication. I have tried every dose of every brand of every combination out there. Once we determined I was a T4 non converter, we focused on T3 only as a treatment. Increasing very slowly over multiple months, we found a dose that finally eliminated all symptoms and I feel great. But…..I’m wondering if the dosage is too high at 75mcg/day taken in divided dosages. I have zero symptoms of hyper. None. What do you think?

  8. I am confused by this article! I had my Dr convert my dosage of Armour to liothyronine based on info I found on this web site. This article does not even sound like the same author of the “Thyroid Medication: Levothyroxine vs NDT vs T3 – Which is Best?” blog entry. I felt so good as soon as I made the change. I seldom take the Armour as it did nothing compared to the liothyronine. Now this article says don’t take T3 long term!!! I have had a problem since I was 11 yo, now 64. I gave up a successful career at 39 because I could not function due to exhaustion. I have been evaluated for so many things, never getting any relief. The lab test does show T3 low (when taking Armour only). When taking liothyronine and taking very little Armour labs showed that T4 seems to stay at a reasonable level and finally T3 went up. Recently after 2 years of liothyronine the TSH test came back at < .01. This concerned my Dr but we put it off for another year because I had a torn rotator cuff and had been treated with several different meds, steroids, muscle relaxers, opioids. These meds resulted in more pain, and a toxic, going crazy reaction. Dr thought these drugs might be the reason my TSH was <.01. Now it is time to go see my Dr. I am so afraid of her removing my access to the liothyronine. Since liothyronine I enjoy life, fog lifting, awake and functioning, being happy. Now I read that taking T3 is only a temporary fix. So are you suggesting I have 1 year of living using T3 and then stop taking it for how long? That time without T3 leaves me back to a life of homebound, excessive sleeping, depression, fuzzy, fearful anxiety.

  9. I agree with the reply above. This story is confusing.
    I have a conversion problem and been on levo/cytomel combination for years but i’ve always felt that i probably don’t need the levo because my labs of tsh en t4 were always in normal range be it on the low side, my t3 however was super low. I remember how much difference cytomel made for my fatigue. Reading this blog and some studies made me more and more suspicious of levothyroxine. I have tried lowering both t3 and t4 but that made me really sick so now i’m back on my old dose. I was however thinking of trying to lower the t4 in the hope i can stop taking it. My gut tells me i only need the t3 but apparently i do need it. And now you write that you can only take it temporarily? I have been taking it for 15 years! Am i going to lose bone tissue and get heart disease and cancer from the levo after menopause? Seriously none of this sounds encouraging.

  10. This article is confusing and the only one on which I have a question mark as it seems contradictory. That said I realise the constraints some doctors are under.

    Some people on T3 Only, are on T3 Only, because only T3 Only works (tongue twister) after trying everything else. Nobody wants to be on T3 Only if they can help it. If they feel well and have labs showing normal T3 levels on T3 Only with symptom remission, why should they come off it and go back to their sick state? The TSH being low is of little consequence after taking T3 the HPT axis is no longer closed and so TSH is no longer a completely reliable measure of anything.

    There’s such a thing as cellular resistance to T3 and many different mutations besides DIO2 can result in cells not getting adequate T3 despite seemingly ‘a lot’ of T3. You take what you need to resolve symptoms. Not everyone does well on the same amount. Some need higher amounts. You quote 50mcg as being ‘high’. That actually is a standard dose for T3 only daily and some need more, 75mcg or higher even. People on lower doses 25mcg etc are often also on T4, so it makes sense you would need more without the backup of the storage hormone.

    The fact one person can get out of bed on a fraction of that amount of T3 and yet some require much more to do the same, points to something more going on. Possibly mutations or something else but once those avenues have been explored and identified or eliminated as causes you need what you need. A double mutation from each parent of DIO2 isn’t something you can do much about for e.g. you can eat as well as you like and take all the vitamins you like you will definitely need some T3.

    This does not correlate with the testimonies of many patients.

    Besides a person who needs it will know if they are taking too much as the symptoms are horrible. I wish I didn’t have to touch the stuff, but I’d like a life and will take it for as long as necessary, because the opposite is no life as it is, I still struggle.

    The advice to the young mother above should have been to try adding some levo and reducing the T3 if possible or even trialing some NDT instead. But if not possible, and she feels well carry on with the T3 Only and then try again in a few years as T4 does have unique benefits and some people find they can tolerate the T4 after some time taking T3. After the advice given she probably feels unduly anxious now that she is doing herself harm.

    • Hi Andy,

      I’m aware of all of the information you mentioned so let me try to distill down my thoughts a little better:

      It is my belief that even without experiencing negative symptoms from T3 use, excessive dosing may cause subclinical problems in the cells which accrue and ultimately lead to serious problems down the line.

      I understand that some people feel that they need higher doses to thrive, I’m just suggesting that this comes at a cost. If you are willing to accept that risk for a better quality of life, that is completely fine as its your choice. But I believe in most situations, there are alternative solutions that can be used to help manage symptoms without resulting in these long-term potential negative outcomes.

      This article wasn’t really meant to discuss these topics in detail so I think I will need to write up an article on this specific topic at some point in the future.

    • Hi Jay,

      You can still gain muscle while using T3, but you do need to be mindful of the dose being used. If muscle gain is your primary goal then you can focus on proper protein intake and proper androgen (testosterone) balance. The combination of diet, androgens, and resistance training will get you what you are looking for.

  11. I recently had an ultrasound on my thyroid gland and it has atrophied. Not much of it left. The weight gain has been large. My current dosage of levothyroxine is 125 mcg. It was adjusted recently from 112 mcg one day and 125 mcg the next. I am 62 and 65 pounds over my ideal weight.
    I am considering T3. Living in Canada with a physician that knows zero about thyroid and doesn’t believe in proactive maintenance. Any advice?

  12. I had thyroid cancer and my thyroid was removed. My dosage of Synthroid is dependent on maintaining a TSh below .1 . I am overweight, losing hair, dry skin and have brain fog. I recently asked my Dr. to prescribe Cytomel , after reading your articles. I take 5mcg but have not noticed any changes. I would like to lose weight and even fasting has not worked. What tests are meaningful for someone with no thyroid to find the right combination of thyroid hormone?

    • Hi Sylvia,

      Testing for those without a thyroid is similar to those with a thyroid. You can find a full list of thyroid lab tests in this article: https://www.restartmed.com/thyroid-tests/

      The primary difference between lab testing in those with a thyroid and those without, is that there’s far less wiggle room or room for error in those without a thyroid.

  13. I was put on levothyroxine and after a few months my blood tests came back with high levels of t4 and my t3 levels had plummeted downwards. It would appear that I don’t convert the t4 at all. I have had anxiety for years so my rt3 levels are probably high but docs won’t test for that no matter how often I ask but then again they wouldn’t test my thyroid function. I had to get an at-home test kit for that in the end which showed I was SEVERELY hypothyroid. So yes, I absolutely WILL be giving t3 a try. A friend cannot absorb t4 and she has been taking t3 for 13 years now and is doing fine.

  14. I am a 69 year old male. My mother had low thyroid, too. I have been on 100 mcg of Levothyroxine first thing in the morning on an empty stomach for over 10 years. Last year, I was complaining of exhaustion in the afternoon, so my doctor added 5mcg of Liothyronine. I’ve been taking it around 2 in the afternoon, and it seems to be helping. Am I taking it at the best time, and would more be indicated if I’m trying to build muscle in the gym (but not get huge like a body builder)? My most recent TSH W/REFLEX TO FT4 reading was 1.32 in February of 2022, but I don’t remember if that was before or after the Liothyronine was added. I do not have any recent readings for T3 or T4.

    • Hi Greg,

      T3 won’t really have an impact on your ability to build muscle so that isn’t really part of the equation. It’s only important insofar as it helps/prevents you from resistance training. Building muscle mass is more about androgen control, protein intake, and resistance training.

  15. I am taking T3 only (25mcg but if I am really tired I have another 12.5mcg in the middle of the day). I have high levels of RT3. My doctor wants to introduce T4 but I have tried twice in the past to take this and each time, at about the three week mark, I seemed to be fatter. Is my body using the extra T4 to make more T3?


  16. If I didn’t take T3 I’d be fighting sleep all afternoon. I’m 65 and @180 lbs. 20-25 lbs. too heavy for my knees, hips, and back health. T3 (Liothyronine) @ 2x 5 mcg daily does nothing to help me lose weight. But I’m glad to take it if it keeps me from going into super hypo mode. Thanks for all your info. for thought.

  17. Awesome article.
    Every time I go through a period of sustained stress, symptoms return. I’ve learnt that for me, if I take a t3 top up, alongside ndt, for a week or until I feel back up to par again, it resolves the symptoms quickly.
    Whilst I do not pay for testing every single time, I believe that reverset3 is up at these times, and the only way to overwhelm it, is give the body what it lacks directly.
    It’s just my theory. It works for me.
    I monitor resting heart rate as an indication of levels. I’m quite fit, so when rhr goes to 70, I know I’ve had enough and back off on the t3.
    I do not recommend anyone does this without clinical guidance. It’s taken many years of discovery and testing to monitor, to find my way.

  18. Hello.
    Could we think that taking exogenous T3 would cause a natural slow down/ adjustment of the endogenous conversion of T4 to T3 as an adaptative compensatory mechanism?
    Isn’t it how it works when we take birth control pill for example, where the exogenous hormone suppresses the endogenous secretion?

    • Hi Nathalie,

      Yes, but you are confusing two different aspects of thyroid function.

      There’s no question that exogenous T3 will shut down the hypothalamic pituitary axis in a dose-dependent fashion but this is separate from its impact on thyroid conversion.

      It’s very likely (I’m 99% sure) that the introduction of exogenous T3 has an impact on the entire thyroid conversion process from T4 down to T1. I say this because I’ve seen changes in thyroid function lab tests with the introduction of various types of thyroid medications, including T3.

  19. Every article I read speaks to those who still have their thyroid, but what about those of us who have their thyroid removed. Mine was removed 12 years ago and since then I have had a change in hair, nails, body temperature and weight gain. Both my endocrinologist and my primary care Dr just pat me on the knee and say that is what happens when you don’t have a thyroid. I take 100mcg L-thyroxine 6 nights a week which manages my T4, but I want to loose the 15lbs I’ve gained in the last 12 years. I am 77 years old and just tired of not being listened to.

    • Hi Ann,

      I have several articles that are specific to those in your situations. Here’s an example of an article that discusses how thyroid removal impacts weight management and, as a result, the thyroid medication required to correct the problem: https://www.restartmed.com/weight-loss-after-thyroid-removal/

      I have written over 500+ articles on various topics relating to thyroid management and only share one per week to my email list. If you ever want to browse through other articles you can use the search function on my website. There’s well over 1 million words worth of information to sift through.

  20. Hi doc., thanks for the info you provide and the very useful links. I have a problem with your suggestion to limit the use of T3 to 6/8 weeks based on your gut feelings, being that the problem is life long.
    Could you provide links that would help clarify the issue.

    • Hi Lula,

      There’s very little data to share as the general standard of care is to avoid the use of T3 except in rare circumstances. As a result, the majority of studies that exist are heavily biased in favor of levothyroxine use.

      I’ve discussed the differences in thoughts in regards to thyroid management of both conventional doctors and alternative doctors in this article: https://www.restartmed.com/updated-hypothyroid-treatment-guidelines/

      If you are looking for a discussion on how they differ, the pros and cons of both, and where I fall in the mix, then I’d recommend checking it out.

  21. Labcorp lists upper limit of Free T3 at 4.4 pg/mL. I believe you mentioned in one of your videos that a Free T3 of up to 10 was fine, as long as you are not experiences any side effects. Could you please expound on this? Also, I am assuming these results are when blood is drawn in the morning BEFORE your daily dose of medication. Is this correct? Thank you!

    • Hi Dave,

      I remember writing an article discussing that my wife had a free T3 value of over 10 and I wasn’t worried about it but that was because of the timing of the dose relative to when she had her labs drawn. But I definitely wouldn’t say as a general rule that a free t3 above 10 is not a problem. Do you remember the context of that statement or can you link me to the article you are referencing?

  22. Yup, I’m doing it right now as my Dr says my levels are fine, when my T3 is only only 2.8 (lab range for T3 is 2.0 – 4.4) I feel like absolute crap, joint pain, constipation, fatigue. I asked my Dr to up my T3 so instead he upped my T4. I have taken it upon my self to take additional T3 daily. I currently take 112 mg of T4 and 50 mg of T3 daily, I’m taking and additional 1/2 T3 which is an additional 12.5 mg daily because I want to see if this resolves my issues.

    • Hi Michele,

      50mcg is definitely a dose that should have a strong physiological impact so if you aren’t feeling better with even slight increases from there then there’s probably some other factor that needs to be addressed.

  23. Hello Dr. Childs,

    I am a 60-year-old woman diagnosed with Hashimoto’s autoimmune thyroiditis 14 years ago. I have been using a levothyroxine (compounded) and SR liothyronine (compounded) combination (dose of liothyronine has increased and decreased over the years, depending on labs and symptom management) with good results. I have also been a bodybuilder (strength training 3-6 x a week for 35 years) most of my adult life. I have been able to find very little information about how strength training/bodybuilding affects the need for thyroid hormone replacement in a person with Hashimoto’s thyroiditis, and also about how lifelong bodybuilding affects inflammation in the body. I would appreciate you sharing anything you might know about these topics. Thank you.

    • Hi Teresa,

      Bodybuilding, in general, isn’t an issue for thyroid function. The negative consequences that can come through bodybuilding are more related to the augmentation of results from dieting, caloric restriction, and the use/misuse of hormones/peptides and other analogues.

      If all you did was eat clean and take advantage of progressive overload then there’s no reason to suspect it would cause any issues. If you, however, underwent the other treatments mentioned above, then there may be consequences on your hormones and thyroid.

  24. Dr. Childs, I had a partial thyroidectomy at the age of 18 and was initially not placed on any thyroid medications. A few years later I was put on Synthroid and then around 9 years ago I was changed to Armour Thyroid 60 mg. I am 57 years old and 1.5 years ago I had my gallbladder removed. Since then, I have had the worst time trying to lose weight.
    My question is can I take the T2 supplements with Armour Thyroid?
    Thank you,
    Lisa Becnel

  25. I was on levo and synthroid, they did nothing, i started on cytomel. I’m increasring it slowly. I’m at 17.5 mcg. I still have hypothyroid symptoms,
    my doctor goes by my labs which are WNL but on the low side 2.5 Free T3. I want to increase it until my Free T3 is at least 4.0

  26. No, I was unaware that T3 was used by the body building community for weight loss. I currently take 20 mcg. of the generic form of T3, but it was a long, hard battle to get any doctor to prescribe it. For 20-30 years, all I ever got was Synthroid, which left me depressed with weight gain, migraine headaches, hot flashes, sleep problems, and terrible debilitating fatigue.

    Even though my labs showed my T3 was very low to non existent, TSH was high, T4 was high, my primary care doctor who told me he would take care of my low thyroid issues refused to prescribe Cytomel. He told me to go to a university hospital setting to get it prescribed. I fired him in frustration and sought out a thyroid surgeon who also was not comfortable prescribing Cytomel, but agreed to start me on a very low dose of 5 mcg., which was too low to be effective. But that was the beginning of my finally getting Cytomel into my system.

    I found another integrative primary care doctor who started increasing my dosage until we found the correct dose. Needless to say, my hormones were unbalanced as I needed testosterone, DHEA, pregnenolone and was already taking bio-identical progesterone and estrogen. I was estrogen dominant. I’m now 70 and feel so much better than when I was in my 30s, 40s, 50s, and 60s, but I still struggle with low metabolism and must fast weekly as I refuse to be fat.

    I have never eaten the standard American diet which is genetically modified chemicals and garbage. I eat organic and bake my own bread using Einkorn flour, which is grown in Italy and is the only flour left in the world which has not been hybridized.

    I am very disheartened by most doctors who know nothing about health and healing, who won’t investigate the root cause of your health problem, but who prescribe pharmaceuticals ad nauseam to treat your symptoms until you drop dead. For those reasons, I have become my own health advocate doing my own research to get myself healed.

  27. Hi. Thank you for the all the info you provide! Much appreciated.
    I’m a 61 yo menopausal woman also taking bio-identical HRT.
    Have been taking compounded T3 (cytomel) 12.5 mcgms bid for decades in conjunction with T4 (synthroid) 112 mcg once per day in am.
    Would like your thoughts on the fact that I take T3 bid. One capsule am on waking and one around 4 pm.
    Also, I still have symptoms of fatigue, cold all the time and no umph when I weight train. I exercise regularly, eat well, get good sleep and have good control on stress. My endocrinologist refuses to give me more T3 because my TSH is almost at 0.
    Any thoughts on this?

  28. Hello Dr Child’s!

    Thank you for your insight and wisdom. I am 46 years old, treated for Graves’ disease in 2017 with radioactive iodine. I have been struggling with weight, energy, and a collaborative working experience with my aging doctor.
    He has been terrible when I try to advocate for feeling better. I tried to tell him that I was lacking energy, feeling foggy, and gaining weight with 125mg of synthroid. He refused to support any blood testing for T4 or T3. I finials found a naturopath who was willing to prescribe 5mg of
    Cytomel. That addition was a game changer for me. Your recommendation to take it at night, even more noticeable. My energy is better, sleep better, but still gaining weight. My TSH levels are suppressed (below 1) so I am concerned about adding more. My
    Naturopath said that TSH suppression is not necessarily bad and better to go by symptoms. My doctor, totally opposite following only by TSH and ignoring my symptoms.
    Can you speak to the TSH numbers? How important is that?

  29. Hypothyroid for 35 years. Synthroid only for 20 years. Total hysterectomy done at age 50 HRT added. Endo added Cytomel 5mcg twice daily to dosage Synthroid 125. Over the years Synthroid and Cytomel doses adjusted. Currently 66yrs old have been on cytomel for 16 years. I now take Synthroid 75 6 days week skipping Sunday and 10mcg cytomel am and 15mcgs midday. Cytomel taken as normal on skip days. Weight hasn’t been issue since addition of Cytomel. Weight never fluctuates more than 5lbs. Also get Testosterone and Estradiol pellets e 12 weeks.

  30. Hi Dr Childs,
    I posted this on July 13th but got no answer. Hoping it’s because you missed it. Would really appreciate your feedback on the questions I asked at that time if possible. Thank you.

  31. Have you seen any issues with T3 raising blood sugar levels? I have used up to 50mcg of T3 only to have it raise my morning blood glucose levels 20+ points higher (above 105) vs my baseline of 85, before I started. I weaned off, retested and back to my baseline. Unfortunately, that also means I’ve put back on an extra 8 pounds thus far, colder body temps, etc. So, I am going back to using the glandular supplements and T2 to see if I can manage my thyroid function while shedding a few pounds.

  32. Dr. Westin,

    I was just switched about 3 1/2 months ago from generic Levo to Tirosint because of conflicting labs, ED visits and hospitalizations. Hypo since age 34, now 60. Problems started with panic attacks after taking Levo in the morning. Anyhow, about 4 weeks ago I told my doctor I have brain fog, dizziness, hair falling out, eyebrows thinning etc. I wanted T3 added and she said to wait another month and give Tirosint a chance. I waited 3 weeks and I could barely function. Zero energy and all symptoms got worse. My T3 labs came back at 64 with a range of 76-181 she put me on 2.5 mcg of Liothyronine. It’s only been two days but I swear I feel a little fatigue lifting. Based on my age and the dose it seems safe to me. I do have some osteoporosis, I walk an average of 3-4 miles per day and stretch and use resistance bans daily. She said she may increase dose to 5mcg daily after 1-2 weeks based on how I tolerate it. What are your thoughts? I don’t have a typical hypo physique. I’m 5’9 and weight 130. I’ve never felt as rotten as I have for the last 14 months when my hypothyroidism took a left turn. Sally


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