Ever wonder how some bodybuilders and fitness models are able to drop weight rapidly within a few weeks or months before their contest or photoshoot?
While strict dieting along with intense training are the primary factors that contribute to this process, many elite athletes will choose to use certain compounds that accelerate the weight loss process in order to make weight for a competition or shed enough body fat for their on-stage appearance.
One of the most potent tools available for enhancing fat loss is T3, most popularly known as Cytomel.
In this article, we’ll provide further insight into the active thyroid hormones of T3 and T4 and dicuss why bodybuilders utilize these hormones during contest prep.
We’ll also review the major side effects associated with their use and provide an in-depth look at how bodybuilders can restore their natural thyroid hormone production following prep.
The information provided in this article is for general informational purposes only. We do not recommend or endorse the use of steroids or illegal compounds for performance enhancement and weight loss.
TL;DR: T3 & T4 for Weight Loss
- T3 and T4 are biologically active thyroid hormones that work together in regulating metabolism.
- Some bodybuilders and fitness models will use synthetic forms of T3, T4, or T3:T4 combo in order to drop body fat rapidly before a contest or photoshoot.
- Some of the potential side effects of using T3 and T4 include having a higher heart rate, excessive sweating, sleep disturbances, and a reduction in lean mass.
- T3 may be taken on its own or in combination with T4.
T3 vs T4
The thyroid gland is located towards the base of the neck and influences a wide variety of bodily processes including brain development, heart function, and digestive function.
It produces the biologically active hormones T3 and T4 which play a major role in regulating metabolism.
T4 (thyroxine) is produced in higher amounts than T3 (triiodothyronine) and functions as a T3 precursor.
Around 40% of T4 in the body is converted into T3 through the process of removing an iodine group from its outer ring (deiodination).
Once converted, the body’s cells use T3 towards delivering oxygen and generating energy within various tissues and glands within the body.
The thyroid gland generates 20% of the body’s total T3 whereas the remaining 80% is created outside of the thyroid gland in other tissues.
Most people secrete between 10-22 mcg T3 and 94-110 mcg T4 each day.
Hypothyroidism vs Hyperthyroidism
Some individuals may be affected by thyroid conditions including hypothyroidism or hyperthyroidism.
In most cases, these conditions are caused by autoimmune diseases but they may also be heavily influenced by dietary deficiencies, surgeries, or the use of certain medications.
Hypothyroidism is a condition where the thyroid is underactive and does not produce adequate amounts of thyroid hormones.
Most individuals tested for hypothyroidism will display low levels of free T3 and free T4 while their TSH (thyroid stimulating hormone) levels are high or test outside of the optimal reference range.
In contrast, hyperthyroidism is a condition where the thyroid is overactive and produces excessive amounts of T4 (thyroxine).
Individuals who test for hyperthyroidism typically have extremely low levels of TSH while their free T3 and free T4 levels are elevated.
Cytomel and Synthroid
Those who are affected by one of the above thyroid conditions will generally need to take medication to obtain proper thyroid function.
Individuals with hypothyroidism will usually take Synthroid (synthetic T4), Cytomel (synthetic T3), or combination thyroid medication that contains both synthetic T3 and T4.
Synthroid, or Levothyroxine, is prescribed by most doctors for the treatment of hypothyroidism as it provides a more mild approach and tends to result in fewer side effects.
However, Cytomel, or Liothyronine, may also be prescribed for hypothyroidism and provides a more aggressive form of treatment.
Some doctors and medical experts tend to shy away from the use of Cytomel as T3 is absorbed rapidly and may lead to mild thyroid hormone toxicity in certain patients.
On the other hand, the use of combination thyroid medication has been on the rise within the last few years and is viewed by many medical experts as a promising solution for thyroid hormone management.
Doctors within North America have noticed an increase in patient dissatisfaction with the use of monotherapy (i.e. synthetic levothyroxine only) and nearly 1/3 of physicians within the US provide treatment in the form of combined T3:T4 therapy.
In fact, a recent study showed that 23 patients who switched to the use of combination therapy over monotherapy displayed major improvements in quality of life and cognitive function.
Cytomel Weight Loss
Due to the more aggressive nature of Cytomel compared to Synthroid, many bodybuilders have used it as a tool for rapid weight loss in order to enhance their performance, make weight, or shed necessary body fat to obtain their desired physique.
Individuals who are not affected by hypothyroidism may obtain synthetic T3 on either the black market or by purchasing it from websites that sell research compounds, such as peptides, SARMs, and the like.
These athletes may choose to purchase T3 in Cytomel form or they may find it in a generic liquid, capsule, or tablet form.
T3 Dosage Bodybuilding
Athletes typically run anywhere from 25-50 mcg on average over the course of 8 weeks to enhance fat loss.
If using a tablet or liquid form, competitors will generally start their dosage at 12.5mcg and then gradually increase their daily dosage by 12.5mcg every 3 days until they reach 50mcg.
They will continue to run 50mcg through the end of their contest, however, some coaches may slowly lower their clients’ dosage a few weeks prior to competition in order to reduce the loss of lean mass or prevent muscles from flattening out the day of the show.
After the completion of their contest, most competitors will use the same protocol for tapering off and drop their daily dosage by 12.5 mcg every 3 days and run the final 3 days of their T3 cycle at 12.5mcg total.
Those who opt for capsule form may choose to run 25mcg for the entire duration or they may follow a similar tapering method depending on each capsule’s concentration.
In most cases, capsules are extremely hard to dose properly, especially if they contain higher amounts of T3, such as 50mcg per capsule.
You won’t see most bodybuilders or fitness models purchasing Synthroid or generic T4 to enhance their physique as T3 is nearly 5x more potent than T4 and under normal conditions, the body only converts up to 40% of T4 into T3.
T4 Bodybuilding Dosage
If using a T3:T4 combo, it’s best to purchase a product that contains a 1:2 ratio.
For example, some competitors will use this thyroid hormone combo in liquid form.
Each bottle typically contains around 30mL and each mL should contain around 100mcg:200mcg of T3 and T4 respectively.
However, it’s best to not exceed a limit of 50mcg:100mcg so competitors should usually only need to use about 0.5mL per day once they’ve reached the peak of their cycle.
In order to enhance fat loss further, some competitors may choose to add on additional compounds during their T3 or T3:T4 cycle.
Here’s a quick glimpse into 2 popular stacks used by bodybuilders during the final weeks of contest prep for a final push.
Clen T3 Cycle
Clenbuterol (clen) combined with T3 is extremely powerful and can further fuel the fire in respect to thermogenesis.
Since T3 is typically limited to 8 weeks of use, competitors may start using clen around 12-16 weeks out from their show.
The starting dosage is usually around 20mcg daily and should be increased in 20mcg increments every 2 weeks until reaching 120mcg.
It’s best to take clen before fasted cardio in the mornings as it will promote better breathing and expand blood vessels.
Some coaches may recommend that their athletes only use clen for 2 days on 1 day off to maintain maximum effectiveness and prevent adrenal fatigue which would hinder the fat loss process.
Clen Yohimbine T3 Stack
Perhaps an even more effective cutting stack for those who can handle it is the use of clen, T3, and yohimbine.
Generally, competitors will only need to use 5mg of yohimbine pre-workout or before fasted cardio and they may use yohimbine on their days off of clen.
An example of how a bodybuilder may use clen and yohimbine together while on T3 is to alternate 2 days on clen followed by 2 days on yohimbine HCL.
Clen should be used in the same way that it would on a T3-clen cycle whereas yohimbine should be taken once or twice daily before training and fasted cardio in 5mg dosages.
Some people may be sensitive to yohimbine so it’s best to test your tolerance to this supplement prior to trying it during contest prep.
T3 Side Effects Bodybuilding
Individuals who currently have a thyroid disorder should not utilize T3, T4, or T3:T4 combination compounds on their own to accelerate fat loss.
Rather, they should consult with a medical professional first as the use of particular compounds may worsen their condition.
Unfortunately, many athletes use T3 as a crutch for attempting to drop body fat while not prioritizing their diet and training.
This may increase the risk for a significant reduction in lean mass and may actually affect a competitor’s look negatively by causing them to look flat on stage.
Some other common side effects of using T3 or T3:T4 combo for weight loss include:
- Rapid heart rate (especially in those using over 50mcg/day)
- Increased breakdown of muscle (why waste all of your hard work away?!)
- Reduced insulin sensitivity (this is not good news, especially for those who are trying to feed into their show and fill-back up)
- Excessive sweating (Talk about night sweats!)
- Impaired cognition and increased agitation (the absolute worst thing to experience when you’re already hangry)
Thyroid Storm Management
If you’re one of many competitors who are lucky enough to experience a thyroid storm when taking T3 then you know firsthand how difficult it can be to manage side effects effectively and find sweet relief.
Many newbies to T3 may experience nausea, excessive sweating, elevated temperature, and agitation within the first few days of its use.
If this occurs, lower your starting dosage by 25-50% and then follow the gradual 3 day taper of increasing your dosage by 12.5mcg, if possible.
You may choose to raise your dosage at somewhat smaller dosages if necessary but generally 12.5mcg works for most people.
This happens quite frequently as your body is still producing endogenous thyroid hormones while taking exogenous synthetic thyroid hormones, thus creating an excess supply of thyroid hormone available for the body to use.
It usually takes at least several days up to a few weeks for the body to shut down its own production of thyroid hormones after starting T3 so it’s acceptable for most people to start at lower dosages for the first 2 weeks of their T3 cycle.
If a thyroid storm doesn’t occur until the peak of your T3 cycle you may be running too high of a dosage (this typically occurs if you exceed 50-75mcg per day).
If you need to lower your dosage at any point throughout your cycle make sure to slowly reduce the dosage and maintain a minimum of 25mcg per day so that your body maintains a similar T3 production as it did prior to taking synthetic thyroid hormones.
At the conclusion of your T3 cycle, it’s absolutely essential for you to restore your body’s natural production of thyroid hormones.
In order to do this, it is recommended to take specific vitamins and minerals as well as ensure that you’re sleeping enough each night and recovering properly to lower cortisol.
Some of the top nutrients to consume in foods or supplements following the use of synthetic T3 and T4 include the following:
- Vitamin D
- B Vitamin Complex
- Antioxidants (vitamins A, C, E, etc.)
Complete Thyroid Panel
We recommend Lets Get Checked for getting a full at home thyroid panel, it’s super convenient since you don’t have to go to the center and wait in line etc. However they don’t test for rT3 (reverse T3).
You should also make sure to obtain a complete thyroid panel every few months post-contest to check to see if you’ve restored proper thyroid function.
Make sure that you ask for the following parameters when getting a thyroid panel as they will detect any abnormalities and provide a full spectrum of evidence for potential disorders:
- Free T3 (fT3)
- Reverse T3 (rT3)
- Free T4 (fT4)
- Thyroid Stimulating Hormone (TSH)
- American Association for Clinical Chemistry (AACC). (2017, March 20). Thyroid Hormone Synthesis and Transport. https://www.aacc.org/science-and-research/clinical-chemistry-trainee-council/trainee-council-in-english/pearls-of-laboratory-medicine/2017/thyroid-hormone-synthesis-and-transport#
- Dayan, C., & Panicker, V. (2018). Management of hypothyroidism with combination thyroxine (T4) and triiodothyronine (T3) hormone replacement in clinical practice: a review of suggested guidance. Thyroid research, 11(1), 1-11. https://thyroidresearchjournal.biomedcentral.com/articles/10.1186/s13044-018-0045-x
- Iddah, M. A., & Macharia, B. N. (2013). Autoimmune thyroid disorders. International Scholarly Research Notices, 2013. https://www.hindawi.com/journals/isrn/2013/509764/
- InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. How does the thyroid gland work? 2010 Nov 17 [Updated 2018 Apr 19]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279388/
- Mayo Clinic. (2020a, November 14). Hyperthyroidism – Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/hyperthyroidism/symptoms-causes/syc-20373659
- Mayo Clinic. (2020, November 19). Hypothyroidism – Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/hypothyroidism/symptoms-causes/syc-20350284
- Paloma. (2021, May 21). Top 6 Vitamins for Hypothyroidism. Paloma Health. https://www.palomahealth.com/learn/top-vitamins-hypothyroidism
- Paloma Health. (2021). Thyroid drugs for hypothyroidism | Paloma Health. https://www.palomahealth.com/medication
- Rousset, B., Dupuy, C., Miot, F., & Dumont, J. (2015). Thyroid hormone synthesis and secretion. Endotext [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK285550/
- Senese, R., Cioffi, F., de Lange, P., Goglia, F., & Lanni, A. (2014). Thyroid: biological actions of’nonclassical’thyroid hormones. The Journal of endocrinology, 221(2), R1-12. https://joe.bioscientifica.com/view/journals/joe/221/2/R1.xml
Bonus Section – 5 Secret Protocols Bodybuilders Use to Get Ripped!
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