Does Cytomel Help with Weight Loss? Dosing guide + How to use it
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Does Cytomel Help with Weight Loss? Dosing guide + How to use it

Cytomel can help boost your metabolism and lead to weight loss, ESPECIALLY in certain hypothyroid patients. 

Does that mean every hypothyroid patient should take it?

Not by a long shot. 

I love this medication and use it frequently, but there are some things you should be aware of if you are considering using Cytomel or Liothyronine. 

​Not taking it correctly may lead to negative side effects...

So let's talk about how to use it CORRECTLY.

More...

What is Cytomel & Why does it work so well? 

Cytomel is a thyroid medication that contains PURE T3 Hormone.

Recall these basics from thyroid physiology:

T4 = INACTIVE hormone and must be converted to T3 to become active <--- This is what most Doctors prescribe (Think Synthroid, Levothyroxine, Tirosint

T3 = ACTIVE thyroid hormone which does NOT need to be converted to become active <--- Most Doctors do NOT prescribe this medication (Cytomel, Liothyronine, SR T3 (1))

Effects of cytomel on various tissues in the body

Reverse T3 = Inactive thyroid metabolite that can form from T4 in the presence of inflammation, stress, poor diet and nutrient deficiencies. 

T4 can turn into T3 or Reverse T3 depending on the conditions of the body.

​So if you have hypothyroidism and you are taking a T4 only medication, you are relying upon your body to do the converting process for you. 

This is why so many patients on T4 only medications do so poorly - their body doesn't convert well.

But if you give someone T3 only medication, you don't have to rely on the body for converting T4 to T3.

Thyroid conversion with leptin resistance

Instead, you bypass this conversion process and allow for more thyroid hormone to enter into target cells and tissues without reverse T3 competition

This provides an instant burst of thyroid hormone to the body and makes it a MUCH more powerful medication.

This also helps explain why Cytomel and Liothyronine can cause negative symptoms if used in high doses.

And this also may explain why Doctors, in general, are not as comfortable prescribing this medication to patients (even though so many patients benefit from taking it). 

This is also why some bodybuilders use T3 medication to boost metabolism and burn fat before competitions. 

How Cytomel Causes Weight Loss

In order to understand why Cytomel causes weight loss, you need to understand the importance of thyroid hormone in your fat cells and mitochondria. 

Your thyroid helps control your metabolism and helps set your basal metabolic rate (2). 

​What that means is your thyroid really helps to control your WEIGHT and the amount of fat you are burning on a daily basis. 

​As many of you know:

Low thyroid hormone = weight gain (one of the primary symptoms of Hypothyroidism)

​But why doesn't that weight go away once you start taking Levothyroxine or T4 hormone? 

It has to do with the conversion process I mentioned above.

If you give the body T4 hormone and it does NOT turn it into T3 then your cells will NOT get the thyroid hormone they need and your metabolism will STAY low.

This benefit has been shown in at least one study (3).

In this study, patients were given LT3 medication in place of their usual thyroid medication at equivalent doses and the researchers found that patients who switched experience an average of 4-5 pounds of weight loss without any other changes

These patients also experience an average reduction of 3-8% body fat.  

All of these were seen simply by changing the dose and without adding in any other therapies!

You can read this blog post for much more info on this conversion process and how it leads to weight gain.

You can also read this post for more info on why levothyroxine doesn't cause weight loss in many patients. 

Cytomel (or other T3 medications) on the other hand do increase thyroid hormone in the body and thus can help boost metabolism and lead to weight loss. 

If that's the case then you are probably asking...​

Should you take Cytomel?

The answer is not as straightforward as it might seem. 

If you've been reading this so far you are probably wondering why you aren't taking T3 medication already.

Or you're getting ready to go ask your Doctor to prescribe it to you...

Well, hang on a second.

Effects of T3 on liver function and fat break down

Cytomel and other T3 containing medications aren't ideal for everyone, but based on my experience many people tolerate them quite well. 

How do you know if you tolerate them?

Most patients who need T3 have one or more of the following:

  • High levels of Reverse T3 (> 15)
  • History of Leptin resistance (or leptin level > 12)
  • History of Diabetes, Pre-diabetes or Insulin Resistance
  • History of Bipolar disorder or a strong family history of Depression, suicide or other mental health disorders
  • History of Fibromyalgia, Chronic fatigue syndrome or Chronic pain syndrome
  • Someone who does NOT feel well on T4 only medications (Synthroid, Levothyroxine, Tirosint, etc.)

Basically, these conditions all are associated with a higher demand for thyroid hormone or a condition known as tissue level hypothyroidism (4). 

​Tissue level hypothyroidism describes a condition where your blood levels of thyroid hormone may appear normal, but your tissues are starving for thyroid hormone.

Tissue level hypothyroidism

This may explain why so many hypothyroid patients are unhappy despite getting "treatment" with T4 only medications (5). 

The presence of any of the medical conditions (or symptoms) listed above may be an indication that you would benefit from using T3 medication. 

Cytomel Dosage and How to Use it Safely

Because Cytomel is stronger than T4 only thyroid medications, you should use some caution when starting and titration your dose.  

It is estimated that T3 is about 3-4 times more potent at altering the TSH when compared to LT4 (6). 

Because of this, it's wise to monitor both your resting heart rate and your basal body temperature each morning if you decide to use this medication. 

​Why?

Because Cytomel and other forms of T3 will directly increase your metabolism thus resulting in a higher body temperature which will also increase your heart rate by acting on cardiac myocytes.

By monitoring both of these variables you can ensure that you are getting an adequate dose while preventing excessive dosing or hyperthyroid symptoms

Try to keep your pulse and resting heart rate within these ranges: ​

  • Body temp no higher than 98.6
  • Resting heart rate no higher than 70-80 beats per minute while resting (note this is different from your resting heart rate while sleeping)

These variables, if combined with thyroid lab testing for total T3 and free T3, will help you determine your ideal dose. 

I recommend using these metrics instead of one-size-fits-all dosing recommendations because the variability between individuals is very large depending on factors such as sensitivity and genetic variance. 

Some patients may do well on small doses of Cytomel (5-10mcg per day) whereas others may need considerably more. 

For instance:

Studies have shown that, in the setting of treatment-resistant depression, Cytomel dosing can be as high as 70-100mcg per day (7). 

If you decide to start Cytomel make sure you start at a low dose and titrate or increase your dose up slowly over an extended period of time (weeks to months). 

A typical starting dose may be as low as 5-10mcg with an increase in dose by 5-10mcg every 10-14 days.

More sensitive patients should start out at even lower doses while patients who have previously tolerated T3 medications in the past may be able to start at higher doses. 

Cytomel vs Synthroid

​Instead of thinking of Cytomel vs Synthroid I want you to think of them as a complementary pair. 

Some people do benefit from Cytomel only (in higher doses), but many people do well on a combination of T4 and T3.

In fact, I would say the majority of people need some combination of T4 and T3 medications because this mimics the natural production of thyroid hormone from your thyroid gland

In a practical way, you can achieve this combination by simply adding Cytomel to your existing dose of Levothyroxine or Synthroid. 

By using both T4 and T3 you will be able to provide your body with both immediate and long-term hormones. 

When it comes to sheer power, Cytomel definitely is stronger than Levothyroxine.

Despite this, you are much more likely to have success in asking for a small dose of T3 compared to asking for a large dose. 

Many physicians are aware of the emerging research which shows that patients prefer combination therapy to monotherapy with LT4. 

When using combination thyroid hormone you will want to shoot for a ratio of close to 80% T4 and 20% T3 as this matches what your thyroid produces naturally

For instance:

If you were taking 100mcg of T4 you would want to be on around 20mcg of T3.

Simply adding T3 to your existing dose of T4 may improve your overall symptoms by helping to drive down Reverse T3 levels and by directly activating cellular transcription.

This is just a rough estimate, however, as each person may need slightly more or less. 

You can, and should, also direct your dosing based off of your thyroid lab tests such as TSH, Free T4, and Free T3. 

Cytomel & T3 vs NDT

I referenced Levothyroxine and Synthroid above because the great majority of patients are on these medications. 

But what about natural desiccated thyroid medications

Is Cytomel better than NDT?

Instead of thinking about which thyroid medication is best, you should consider the specific needs of your body. 

NDT contains a static combination of both T4 and T3, each grain of NDT has about 38mcg of T4 and 9mcg of T3. 

If you calculate out the ratio you will find that the majority hormone in this formulation is T4 (about 76%). 

This means that even with higher doses of NDT, patients are still susceptible to reverse T3 pooling.

So, even though the medication contains some amount of T3 it may not be sufficient for certain patients.  

In a general sense, the sicker the patient (more medical problems, high blood pressure, cholesterol issues, insulin resistance, etc.), the more likely they are to need higher doses of T3 compared to T4. 

So again, T3 can compliment patients already using NDT quite well.

The addition of Cytomel and liothyronine to existing doses of NDT provides an additional boost of T3 and skews the ratio of T4 to T3 more in favor of T3.

This allows for less competition at the cellular level between T3 and Reverse T3 which can result in more weight loss and fewer symptoms (8). 

  • Note: If you are adding Cytomel to an existing dose of NDT due to reverse T3 pooling issues you will likely need to decrease your total dose of NDT to reduce serum levels of T4. 

Sustained Release T3 (SR T3) vs Immediate Release T3

T3 comes in two different varieties:

  • Immediate release: Cytomel and Liothyronine
  • Sustained release T3: Compounded and generally bound to methylcellulose

They both contain the active ingredient triiodothyronine but differ in how quickly they are absorbed into your gastrointestinal tract after ingestion. 

Why would you care about how quickly the T3 is absorbed into your body? 

It turns out that immediate forms of T3 are rapidly absorbed and spike serum T3 levels in the body within a few hours after ingestion (9). 

The fact that your serum levels rise in this time-frame isn't really the problem.

The potential problem is that some tissues (mostly cardiac tissues) are very sensitive to T3 hormone.

The majority of thyroid hormone receptors in the cells respond through a nuclear receptor which results in changes to genetic transcription (changes in enzymes, DNA, etc.).  

But, in cardiac tissues, T3 has a direct ionotropic and chronotropic effect (10). 

This means that higher doses of T3 can directly result in an increased heart rate and an increased force of contraction in the heart. 

These changes may manifest clinically as heart palpitations or a rapid heartbeat. 

Generally the sensation of palpitations is more concerning to the patient than it is medically relevant, but obviously, an increased force on the heart is not a good thing either. 

This is where SR T3 comes into play...

Patients who are sensitive to T3 or who have a tendency to lean towards heart palpitations tend to do better on the sustained release version of T3.

The delayed release allows for more stable serum levels of T3 which means your cardiac tissue doesn't get hit with a high dose all at once.

​SR T3 can also be used in patients who want fewer inactive ingredients in their medication because compounding pharmacies can control what ingredients they formulate the T3 with (to some degree). 

​This is helpful for patients who are very sensitive to medications, supplements and generally have adverse reactions to inactive ingredients. 

A few things should be noted about SR T3 however:

1. SR T3 can be tougher to digest so isn't necessarily the best choice in patients who have multiple GI issues or difficulty with absorption.

2. Due to digestive issues, SR T3 may not be fully absorbed which means that the dose is less efficacious than IR T3 versions. This means that 10mcg of IR T3 ingested will not necessarily equal 10mcg of SR T3 ingested.

If you are contemplating switching from IR T3 to SR T3 it's important to consider these variables as they may alter your dose. 

Cytomel Symptoms & Side Effects

If you are starting T3, Cytomel or SR T3 then there are some side effects you should be watching out for.

Most side effects come from taking too much medication and result in hyperthyroid-like symptoms but the symptoms from Cytomel tend to be a little bit different from overt hyperthyroidism. 

Common side effects of Cytomel include: 

  • Hair loss (usually goes away after 2-3 months)
  • Heart palpitations
  • Increased heart rate
  • Increased body temperature, hot flashes or warm flashes
  • Weight loss (most common) weight gain (uncommon but does happen)
  • Jittery sensation or increased anxiety
  • Headaches
  • Loose stool or diarrhea

These tend to be the most common side effects patients experience when starting or increasing the dosage of Cytomel but that doesn't mean that they are necessarily common.  

When you are replacing thyroid hormone that is deficient in your body you should only have positive side effects. 

If you are experiencing negative side effects then that may be an indication that your dose is too high or that you increased your dose too rapidly over a short period of time. 

Occasionally, when starting Cytomel or other T3 medications, the starting dose can be over stimulating and may temporarily cause some of the symptoms above. 

Usually, these symptoms will subside, especially when starting out on a low dose, but sometimes nutrient deficiencies and other hormone imbalances can make it difficult to tolerate T3. 

You'll know that Cytomel is working if you experience any of the following positive side effects: 

  • Weight loss
  • Increased energy
  • Decreased hair loss
  • Increased cognition and improved memory
  • Decreased brain fog
  • Improved sleep

When starting T3 you should experience most of these symptoms and none, or very few, of the negative side effects listed above. 

Improving T4 to T3 Conversion with other Thyroid Medications

​What if your Doctor isn't willing to prescribe Cytomel? What are you supposed to do? 

If you can get your Doctor to test your free T3 levels and show that they are quite low most physicians are willing to add in T3 hormone. 

But this isn't true of all Doctors.

If this just isn't an option for you, then you will want to focus on T4 to T3 conversion and do whatever is in your power to increase this conversion process.

Factors such as taking certain supplements, adopting a healthy exercise routine, changing up your diet, and reducing your stress can all impact thyroid conversion. 

​If you can promote T4 to T3 conversion then you will necessarily reduce T4 to reverse T3 conversion

By reducing T4 substrate and "forcing" your T4 to convert to T3 you are effectively lowering the reservoir of T4 that is capable of converting to reverse T3.

This has a great impact on your body and your symptoms.

The higher your free T3 the more active your thyroid hormone is, the lower your reverse T3 and the higher your metabolism will be.

​But realize the opposite is also true:

The lower your free T3 and the higher your reverse T3 the slower your metabolism will be and the more likely you will be to experience symptoms of hypothyroidism. ​

Cytomel Reviews & Case Studies

I've included some Case studies from my practice of patients who have used Cytomel, Liothyronine, and T3 to help with weight loss. 

You can read them here: 

I've found that up to 60% of patients that come to see me need T3 in some form (either Cytomel, Liothyronine or SR T3). 

If you are taking some other form of thyroid hormone (levothyroxine, Synthroid or even forms of NDT) and you aren't getting improvement in your symptoms or you aren't noticing weight loss then improving your T3 levels might help.

Generally adding T3 or Cytomel isn't enough to cause significant weight loss by itself, but it is almost always required in order for the body to get into "fat burning mode". 

As you can see from the case studies above T3 is always PART of the therapy, and in some cases, therapy revolves around thyroid dosing, but other therapies are almost always required for 40+ pounds of weight loss.

Conclusion

Cytomel is a powerful thyroid medication that can help boost metabolism and lead to lasting weight loss in certain patients. 

Having said that, Cytomel is NOT for everyone. 

Use the information in this post to help determine if Cytomel would be helpful for your case and remember that each person is unique. 

If you decide to try Cytomel out then I recommend starting with a low dose and titrating SLOW. 

While using Cytomel make sure to monitor both your resting heart rate and basal body temperature to ensure that you do not overdose yourself. 

Now I want to hear from you!

Have you used Cytomel successfully to lose weight?

Did it work for you?

Why or why not?

Leave a comment below!

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.