Growth Hormone and Its Effect on Thyroid Function

Many of us have used growth hormone in the hopes that it will accelerate fat-loss because that is what we have heard and seem to observe in higher level athletes and bodybuilders who are lean. What many do not realize is the actual mechanism of how growth hormone works to increase fat burning can actually decrease the fat burning ability of thyroid hormone. As we know, T3 and T4 are the two forms of functional thyroid in the body and GH will effect the blood level and efficiency of both of these hormones.

When GH is first elevated in the body from an exogenous source, fat-burning is increased through multiple mechanisms but is increased through an increased activity of the active T3 hormone. Growth hormone does this by a very distinct manner in which the enzyme 5'(prime) deiodinase is dramatically enhanced. This creates an increased conversion of the storage T4 to the active T3. With more active T3, the body begins to burn fat at an accelerated rate.

The catch is that the body has a limited amount of total and T4 thyroid hormone. After a few weeks, the body has a lower level of T4 because of the increased activity of the 5'deiodinase enzyme converting much of the T4 to the active T3. If T4 is not also supplied exogenously, the T4 levels will run low. At this point, the increased fat burning boost provided by the GH begins to decrease. Eventually, the fat-burning effect from the GH dwindles to nothing.

The way around this short-term accelerated effect of GH in order to make the fat-burning last is to supply the needed T4 to the body at a low-moderate dose (50-75mcg). By supplying the body with extra T4 the GH has more to work with and continues to pump out extra T3. This will allow you to milk the GH fat-burning effect for all its worth and get much more from your hard earned money (we all know that GH is NOT CHEAP).