Know your body: Aromatase

Aromatase Enzyme

In your efforts to promote muscle growth and reduce body fat, there are certain bodily substances that you should know about – that is why we have started a new series entitled “Know your body”.

Up first is Aromatase.

“The aromatase enzyme complex catalyses the conversion of androgens to estrogens in a wide variety of tissues, including the ovary, testis, placenta, brain, and adipose tissue” (Morishima et al., 1995). To state this in more lay terms: Aromatase is a key enzyme in the biosynthesis of estrogens, more specifically for the aromatisation of androgens into estrogens and this happens in various tissues e.g.. fat cells. To further summarise: This enzyme converts the desirable muscle building & fat burning hormone Testosterone, into the less desirable hormone estrogen.

In saying that, Aromatase plays an important role in our overall health, so even while estrogen might be the feared by most bodybuilders, the reality is it is very important for bone health (Chien and Goss, 2006) & bone maturation (Carani et al., 1997). So lets look at what happens when aromatase gets out of balance:

Too much aromatase, will result in an individual having the same problems that develop from having excess estrogen:

  • Inhibited androgen production (through a negative feedback loop that results in your body producing less testosterone)
  • More prone to fat storage
  • Males are more prone to developing gynocomastica (developing breasts)
  • Males more prone to reproductive issues

Too little aromatase, (which is almost naturally non-existent) will result in an individual having the same problems that relate to having low estrogen:

  • Delayed closing of the epiphyseal plates
  • Decreased bone mass
  • Decreased sex drive

Almost everyone need to be actively concerned about having too much aromatase due to our modern lifestyles, as the following factors increase aromatase activity:

  • Alcohol consumption
  • Sugar consumption
  • Being over-weight

This is yet another reason why your trainer will tell you to curb your alcohol & sugar consumption.

So what is the take home message?

  • Sugar and Alcohol consumption will make you comparatively more feminine hormonally (more estrogenic) , which then results in you being more prone to storing fat (this is yet another reason why the moronic “if it fits your macros” approach just doesn’t pan out in reality).
  • The fatter you get, the more feminine you get hormonally, which results again in you being more prone to getting fatter. As you can see this is a vicious cycle.
  • Certain supplements/foods can help with decreasing aromatase activity (but this is the subject of another post).


Carani, C., Qin, K., Simoni, M., Faustini-Fustini, M., Serpente, S., Boyd, J., Korach, K. and Simpson, E. (1997). Effect of testosterone and estradiol in a man with aromatase deficiency. New England Journal of Medicine, 337(2), pp.91–95.

Chien, A. and Goss, P. (2006). Aromatase inhibitors and bone health in women with breast cancer.Journal of Clinical Oncology, 24(33), pp.5305–5312.

Morishima, A., Grumbach, M., Simpson, E., Fisher, C. and Qin, K. (1995). Aromatase deficiency in male and female siblings caused by a novel mutation and the physiological role of estrogens. The Journal of clinical endocrinology and metabolism, 80(12), pp.3689–3698.

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  1. […] To understand this mechanism, at Eastside Fitness we suggest that all out clients have a read of: Know your body: Aromatase […]

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