9 Factors That Influence Testosterone Levels

Inline_Factors_That_Influence_Testosterone_09.06.17In the last several weeks testosterone has come up on a pretty regular basis. I’ve written about it before, of course, but there’s something about the novel elements (e.g. solar irradiation for certain choice body parts) in recent conversations that’s kept the exchange going.  I thought I’d pull back from the peripheral findings a bit today and re-center the discussion.

As you know, testosterone plays a pivotal role not just for libido levels (although we won’t leave that out), but also for bone density, protein synthesis and muscle building, hair growth, estrogen production, red blood cell production, sperm production—amid other key functions in the body (for men and women by the way).

So, what are some factors that influence testosterone levels for the better and worse for both genders? What are the mechanisms behind these associations? And how do they relate to a healthy Primal life?

Let’s dig in…

Understanding the Testosterone Spectrum

The first question that always comes up is what “normal” or desirable levels should be. As with many of the measurements and markers we seek out, I tend to trust how I feel more than what a single number in time reflects. It’s one thing to suspect you might have a deficiency based on symptoms, but it’s another to talk lab values.

Are you experiencing low energy, low libido, breast development (in men), expanding waistlines, infertility, erectile dysfunction, bone weakness, genital numbness, depression, or reduced muscle mass? (Assuming poor lifestyle habits aren’t behind these…)

My preference at this point would be seek out something like a 24-hour Dutch test. These kinds of tests, which take both urine and saliva samples across the course of a day, can provide a more accurate picture of your hormonal situation, shedding light on hormonal interplays and recognizing that the relationships between testosterone, estrogen, cortisol and certain other hormones matter.

And while I’d like to say you could interpret these results yourself, it’s probably best not to rely solely on that. Consider enlisting the help of a holistic practitioner or Primal Health Coach to guide you through the process of looking at the full picture. This way, you’ll have support for making change that works for you individually, and I don’t have to make troublesome sweeping statements of what a “normal” testosterone level would be for a man or woman of X age. The truth is, it’s almost always more complicated than that. A study out earlier this year attempted to clarify the question for men at least, but as you’ll note—it’s not about hitting an exact number by any stretch.

What Impacts Testosterone?

Back in the day, ancient Greeks were known to knock back a goat testicle or three to boost stamina and athletic performance, while ancient Chinese remedies for impotence continue to prescribe the consumption of various unfortunate animals’ reproductive organs. 

But while feasting on the testicles of a goat or the penis of a tiger won’t result in any appreciable gains, certain social, dietary and physiological changes can.

Vitamins and Minerals

While nothing beats a well-rounded Primal eating regime, there’s certain vitamins and minerals that play a distinctive role in T levels. Of course there’s vitamin D, one of the most critical vitamins in the human body (and something most Americans are deficient in). Whether you synthesize it from sun exposure or pop a couple quality, high-potency supplements each day, some research suggests that increased circulating vitamin D in the body correlates to elevated T. Other studies suggest otherwise, but there’s certainly no harm (and a lot of benefits) in getting a bit more D in your life.

Animal testing also suggests that getting adequate levels of vitamin C each day could boost testosterone. A study that gave male rats either 500 or 250 mg/kg ascorbic acid per day found that epididymal sperm concentrations and plasma testosterone were both significantly increased compared to the control group. Another study found that both vitamin C and E were beneficial for improving rabbit semen quality (and by association, testosterone), and that vitamin E appeared even more effective than C.

And then there’s zinc. I’m always a little hesitant to supplement with this trace mineral as it’s easy to go overboard (and needs to be balanced with copper intake), but zinc appears to modulate serum testosterone to a notable degree. A deficiency likely means a drop in T, while supplementing up to normal levels can restore healthy levels. Stick to zinc-rich foods like oysters or grass-fed beef and you should be just fine.

Too Much Green Stuff, Not Enough Meat

This one will come as no great surprise to those of a paleo or Primal inclination: red meat consumption supports healthy testosterone levels. Not only is it an excellent source of zinc, it’s also the most potent source of the amino acid carnitine, which has been linked to improved fertility. The high saturated fat content of the likes of beef and lamb, along with a decent omega 3-6 ratio in pastured versions, doesn’t hurt either.

With those kind of stats, it’s easy to see how a diet lacking in red meat might spell danger for testosterone. Veering away from meat consumption can also result in a calorie deficit for some who aren’t paying attention, which may in turn contribute to reduced T synthesis.

Resistance Training 

As you well know, I’m a huge fan of lifting heavy things, one reason being it’s beneficial influence on testosterone levels. As this 2017 study shows, the rise in T activity following an intense bout of resistance exercise is temporary but significant, the effects of which can be felt several hours afterwards.

Generally speaking, the heavier you lift the better, with research suggesting that resting 90 seconds between sets may promote the greatest T mobilization. Another study found that professional rugby players’ testosterone levels responded best to a workout consisting of 5 sets of high pull, bench press, squat and chin-ups at 15 reps each, this time with a 1-minute rest. There remains a lot of variation between studies, so play around with different resistance regimes and see what works best for you.


My other great love when it comes to exercise is sprints, and these too can work wonders for your ailing T levels. The beauty of these short, sharp bursts of energy is their ability to keep cortisol, testosterone’s arch-nemesis, to a minimum. A 2016 study found that 5 bouts of ten-second sprint cycling promoted a significant rise in T compared to control groups, for both men and women. Interestingly, those with higher pre-test T showed a smaller T response to the sprints. Another study indicated that athletes who exhibit good sprint capacity tend to have a higher basal T level.


On the other hand…here’s another reminder to ditch the chronic cardio and not shortchange recovery. A study that followed a professional soccer team over the course of a competitive season found that testosterone levels steadily declined over the course of the season, with corresponding increases in cortisol. Unsurprisingly, the soccer players exhibited a decrease in muscle mass and increase in fat from overtraining and overexertion—not ideal for professional athletes or anyone.

Likewise, professional basketball players, for example, tend to show a steady decrease in total testosterone over the course of a season. Another basketball study found that the higher the average playing time of each player over the course of a season, the lower their T.

When we look at endurance-type exercise and sports, the same holds true. A 2014 study that examined the hormonal impacts of ultra-marathons in men found that testosterone levels were markedly decreased post-race, with those depleted T levels still apparent a day later. Even in considerably shorter endurance runs, it appears that testosterone levels tend to take a bit of a dive.

Continue training if you must, but be sure to prioritize good overall Primal health and ample recovery. You may also consider supplementing with stress-alleviating supplements like certain adaptogens.


As I’ve already mentioned, when cortisol is elevated, testosterone is diminished—that’s why exercising too frequently or too long is bad news for T. When both are in balance, they complement each other nicely—cortisol promotes muscle wasting and fat gain, while testosterone facilitates muscular hypertrophy and development of lean mass.

But with your hormonal balance out of whack, cortisol can reign supreme. When the body is in a state of chronic stress (physical, emotional, or both) it can be difficult, if not impossible, to achieve those testosterone gains you’ve been striving for. The solution, then, is to stay well away from stress wherever possible.

Add to this mindfulness and meditation for alleviating stress (and therefore elevating T) and getting plenty of sleep. You know the drill…. It doesn’t matter how healthy your habits are—cortisol will remain elevated and T deflated if you’re in a constantly sleep-deprived state.

Healthy Fats

Research shows that low-fat diets are a poor choice for maintaining healthy T levels. Ironically, much of the research demonstrating this principle was conducted in the 1980s, when the low-fat craze was building steam. 

Those studies may be old, but they were relatively conclusive in their findings. One published in 1983 showed significant reductions in total T concentrations after switching healthy middle aged men to a low fat diet. Another, published a year later, demonstrated that cutting men’s fat consumption from around 40% to 25% reduced their T levels significantly, but that this drop could be easily reversed simply by upping the fat content once more. A similar 1987 study found that testosterone exhibited much the same response in women after switching to a low-fat diet.

And while it’s more than a little difficult to ferret out the influence of different types of fats on T levels, the limited available evidence certainly supports the argument for healthy fats over typical polyunsaturated forms. This study, for example, found positive correlations between both monounsaturated and saturated fats and T levels, while pro-omega 6 polyunsaturated fat consumption showed a negative correlation. Another study showed that consumption of monounsaturated fat-rich argan and olive oils resulted in significant T increases.

Considering the average Primal diet is rich in both these fats, you should be just fine on this front. If you’re employing keto as a tool in your Primal arsenal, that works great, too. The higher healthy fat intake may offer a boost. Just be sure you’re not chronically low in total caloric intake (those who are trying to lose weight don’t need to worry and can prioritize the weight loss, which can have its own positive impact on testosterone). 


The influence that estrogen holds over testosterone ideally deserves its own post, but (for the sake of this already-lengthy piece) I’ll keep it brief. In most scenarios, excess estrogen (i.e. estrogen dominance) means diminished testosterone, a condition that affects both sexes but is far more common in women.

At this point, we can turn our attention to one of the leading culprits of hormonal imbalances and low T in women: oral contraceptives. On average, most oral contraceptives are 600 times more powerful in stimulating the synthesis of sex hormone binding globulin (SHBG) than the natural estradiol produced in our bodies. SHBG binds to sex hormones like testosterone, meaning oral contraceptives can dramatically lower both free T and total T in those women.

Of course, there’s plenty more environmental estrogenic overloads to blame here. Xeno-estrogens, synthetic compounds that mimic estrogen in the body, come from a myriad of sources—most notably from plastics like PVC or the inner coating of cans. While there’s a host of BPA-free plastics now on the market, your best bet is to stay well away from plastics in general.

Other contributors to high estrogen include poor liver function, which otherwise facilitates the excretion of excess estrogen from the body, and weight gain, which increases conversion of testosterone into estrogen

Competitive Behavior

Testosterone influences aren’t limited to the physical. A 2015 study set out to examine the theory that societal expectations of gender influence testosterone production in both men and women. Researchers conducted tests designed to measure whether the act of wielding power, a decidedly masculine role in most societies, could actually elevate testosterone in both sexes. Turns out it could. They concluded that “cultural pushes for men to wield power and women to avoid doing so may partially explain, in addition to heritable factors, why testosterone levels tend to be higher in men than in women.”

Of course, this isn’t to say that if the exact same societal expectations were placed on both sexes, everyone would have relatively similar levels of testosterone. Biologically speaking, that’s wouldn’t make sense. What it does suggest is that “wielding” a sense of strength in our own lives may influence our testosterone levels. This isn’t an endorsement of narcissistic power games or chauvinistic attitudes. For me, competitive sports (especially individual ones) seem the logical answer, and research supports that choice. Failing that, one could always explore the murky waters of financial risk-taking. As for me, I’ll stick with a game of Ultimate.

But don’t expect these findings to be reflected in contemporary testosterone treatments any time soon. An article published a few months after the power-wielding study raised serious questions about the validity of that study, pointing out discrepancies in gender groups sizes, confounding factors with control conditions, and potential issues with the way in which they measured T. Still, while the findings are by no means cut and dry, the overwhelming consensus is that competitive behaviors very much play a pivotal role in testosterone production.

Nonetheless, there are two sides to competition as everyone knows with the potential for negative as well as positive responses. How we incorporate competition into our lives in healthy ways is an intriguing and personal question, but the takeaway here for me is an invitation to play more than power. What say you?

Thanks for reading, everyone. Thoughts, questions, requests for follow-up information or commentary? Share them below, and take care.

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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