Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...Tell Me More
Last week’s primer on testosterone garnered a ton of responses, mostly positive, but there appeared to be a bit of confusion regarding testosterone’s role in the female body. Namely, folks seemed to think I was suggesting it played almost no role at all! I tried to be as clear as possible – testosterone is an absolutely vital hormone for women – but I’ll try to be clearer. There’s just that niggling, pervasive stigma of testosterone as the sole hormonal realm of big burly men with bulging muscles, and I guess it’s hard to shake, even for my enlightened readership. Perhaps it’s because we’ve been subject to years of simplistic, substandard health and nutrition advice, black-and-white proclamations that attempt to describe the complex inner workings of the human body with a few sentences.
The reality is confusing and complex, sure, but when it’s reduced down to simple declarations, it’s made even more difficult to comprehend. As a result, there’s a ton of misinformation regarding women and testosterone. Some have the idea that women are unable to produce the stuff – that it’s only produced in the testicles (as if women and men are of different species or something). Others seem to fear testosterone, as if a bit of weight lifting and meat eating is going to flood their bodies with pure, unadulterated testosterone whose sole goal is to synthesize puffy muscles, convert lilting squeaks to husky baritones, and implode breasts to make way for muscular mounds. We have the notion that estrogen and testosterone are mortal enemies, waging bitter hormonal war as each tries to gain a foothold.
The reality, of course, is that testosterone is vitally important in the female body. It plays a huge role, and it does a few really important things. Women (and men) may consider testosterone to be the masculine hormone, but they’d definitely notice if it suddenly went missing from their lives.
Young women produce most of their testosterone in the ovaries. The rest is actually produced in body fat and skin tissue in response to the hormones DHEA and DHEAS, from the adrenal glands, and androstenedione, from the ovaries. That’s also where estrogen is produced.
Female libido is inextricably linked to testosterone. A common side effect of hormonal birth control is elevated levels of sex hormone-binding globulin, or SHBG. Its function is right there in the name – it binds to the sex hormones, especially testosterone and estradiol, and inhibits their function. Reduced bioavailability of testosterone means less desire for sex. You can want it all you want, but without the right hormonal balance, which includes plenty of testosterone for men and women, you’re not going to want it.
As women approach menopause, they produce far less testosterone (and they weren’t producing a huge amount to begin with) and experience far less sexual desire. Causation? Definitely. Female testosterone therapy can increase libido and restore sexual relations to a relationship (which, unfortunately, are often bereft of sex – I wonder why…). I’m not suggesting hormonal replacement therapy; I’m just pointing out that increasing testosterone in women does increase libido. So that’s one function.
Estrogen is made from testosterone. Yes, you heard me correctly. Without testosterone, women would be unable to produce estrogen.
Wait – let me back up a second and provide some detail. Testosterone is responsible for the production of estradiol, which is the primary estrogen in non-pregnant women, up until menopause hits. After menopause, estrone is produced, and in pregnant women, estriol is produced. For our intents and purposes, I’ll continue using “estrogen” when referring to the “feminine” hormone produced from testosterone.
We can all agree that estrogen plays an important role in female (and male) function – a post is probably in order, in fact – and it’s all made possible by the presence of testosterone.
Just as in men, testosterone is responsible for the acquisition of lean muscle mass in women. We’re all human, remember, and hormones play similar roles in our bodies, regardless of gender. But because women have far less testosterone, packing on serious amounts of muscle simply isn’t going to happen naturally. The internal wiring necessary for muscle building is in all of us, though, as shown by the results of female exogenous testosterone usage.
Birth control pills have another unintended, unwelcome side effect: they lower bone density in females. The article doesn’t mention it, but I figure increased binding of testosterone by SHBG is probably to blame. After all, we know that testosterone and libido are linked in both sexes, and that anything that decreases the bioavailability of serum testosterone – like birth control pills – also decreases libido. Last time I mentioned that testosterone is responsible for proper bone mineralization, in both men and women, and this BC study seems to bolster that claim.
It’s true that women produce far less testosterone than males – roughly 1/10th as much, by most accounts – but their sensitivity to testosterone is far greater. Quite simply, women don’t need as much raw hormone to handle business. It’s no less important for women, and it plays the same roles and enables the same functionality as it does in males.
It’s just a matter of scale.