Using Cytomel (T3) For Weight Loss

What Is Cytomel?

Cytomel (chemical name liothyronine sodium) is a synthetic form of the T3 (triiodothyronine) thyroid hormone, and it is prescribed to treat hypothyroidism - thyroid hormone deficiency. In fact, cytomel is essentially the same thing as T3, being the only difference that cytomel is just the synthetic form that people take orally, whereas T3 is naturally produced by the body.

t3 liothyronine sodium

Fig 1. Liothyronine sodium (T3)

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How Does Cytomel Work?

The thyroid gland takes iodine and converts it into the thyroid hormones T4 (thyroxine) and T3. Interestingly, every single cell in the human body depends upon the thyroid hormones T4 and T3 for regulation of their metabolism. Consequently, I hope you can see where cytomel supplementation can come into play for weight loss. T3 is about five times the strength of T4, but under normal conditions the thyroid gland produces only about 20% T3 and 80% T4.

t3 vs t4

Fig 2. T3 vs. T4 Chemical Structure

Like most hormones within the body, the thyroid gland is regulated by the pituitary gland, and when it senses an inadequate level of thyroid hormones, it will secrete thyroid stimulating hormone (TSH), which stimulates the thyroid glands to increase T4 and T3 production. Keep in mind that the body is very sensitive to changes in caloric levels, so after following a reduced calorie diet for an extended period of time, the pituitary gland will decrease TSH levels, resulting in a decreased level of thyroid hormones in the body. This is part of the reason why most dieters hit a plateau in their diet, in spite of making no changes to their diet or training protocol.

Cytomel For Weight Loss

When dieting for an extended period of time the body will decrease thyroid hormone production, since our bodies will be in survival mode. This is something completely logical because a low calorie intake meant to the prehistoric man that famine was approaching and the body would down regulate thyroid hormone production as a defense mechanism to starvation.

Therefore, supplementing with cytomel when dieting will keep the body’s thyroid levels at the original level, so it will prevent the decrease caused by a lack of calorie intake. This is the conservative way to use cytomel. Furthermore, supplementing with cytomel at dosages beyond the body’s natural production will give the individual an even greater base line metabolic rate. As you can see, this is the more aggressive approach, but yet effective.


Dosages Of Cytomel

Under normal conditions, the human body will produce approximately 94-110 micrograms (mcg) of T4, and 10-25 mcg of T3 per day. Individuals looking to ‘play it safe’ will usually incorporate a low dosage of around 10-20 mcg T3 into their weight loss supplement plan in order to keep their thyroid hormone levels at the level they would be at before starting their diet. Meanwhile, those looking to take a more aggressive approach, such as a physique athlete (bodybuilding etc.) looking to achieve an extreme level of conditioning, will take that same 10-20 mcg dosage of T3, but will supplement with it 2-5 times per day. However, when taking the more aggressive approach one should slowly ramp up their cytomel dosage over the course of weeks, and a dosage of 100 mcg per day should never be exceeded.

Cytomel use by females

Females usually respond to cytomel supplementation the same way men do. As a matter of fact, the only reason why females usually use lower dosages than males is because of a smaller body weight and lean body mass.


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