Testosterone and Confidence: The Winner Effect

Think about the last time you watched a guy walk out of the gym, or close a deal, or win a pickup game of basketball. There's a swagger to it. His shoulders are back, his chin is up, and for the next few hours he feels like he could run through a wall. That feeling isn't just in his head. Some of it is chemistry, and a big part of that chemistry is testosterone.

I'm Dr. Farhan Abdullah, and at Magnolia Functional Wellness in Southlake, I spend a lot of my week talking to men about hormones. The conversation almost always starts with the obvious stuff: energy, libido, muscle, belly fat. But the thing that keeps men coming back, the thing they have the hardest time putting into words, is confidence. They'll say something like, "Doc, I just don't feel like myself anymore." What they're often describing is the quiet erosion of a feeling that testosterone helps create.

So let's talk about the "winner effect." It's one of the most fascinating loops in human biology, and once you understand it, you'll never look at a winning streak (or a losing one) the same way again.

What the "Winner Effect" Actually Is

Biologists noticed something strange decades ago while studying animals. When two males compete and one wins, the winner's testosterone rises. That's not the surprising part. The surprising part is what happens next: that elevated testosterone makes the winner more likely to win his next fight, even against a tougher opponent. Victory primes the body for more victory. Researchers called it the winner effect, and for a long time the open question was whether it shows up in people too.

It does. A 2014 randomized study by Samuele Zilioli and Neil Watson, published in Psychoneuroendocrinology, put pairs of men through head-to-head competitions on two consecutive days and tracked their saliva testosterone the whole way through (Zilioli & Watson, 2014). The men who got a testosterone bump after winning on day one performed better on day two. And the men who lost both days? Their testosterone took the steepest dive of anyone in the study. Win and your body leans in. Lose and it pulls back. That's the loop, measured in a lab.

Here's why this matters for the way you move through the world. Testosterone doesn't just respond to outcomes. It shapes behavior going forward. It nudges you toward risk, toward initiative, toward putting yourself out there again. Confidence, in other words, is partly a feedback system. And like any feedback system, it can spin up or it can spiral down.

The Biology Behind the Bravado

Why would the body link a hormone to social standing at all? The classic explanation comes from a 1998 review by Allan Mazur and Alan Booth called "Testosterone and dominance in men" (Mazur & Booth, 1998). Their model is what's known as the biosocial theory of status. The short version: testosterone encourages dominant, assertive behavior, and the experience of dominance (winning, earning respect, rising in a hierarchy) in turn raises testosterone. It's reciprocal. The hormone and the behavior feed each other.

Now, dominance is a loaded word, and I want to be careful with it. I'm not talking about aggression or about steamrolling other people. In a healthy man, what this system actually produces is something much more useful: the willingness to act. The capacity to walk into a room and take up space without apologizing for it. The steadiness to make a decision and stand behind it. That's the everyday face of testosterone-supported confidence, and it has very little to do with chest-thumping.

The same research group went on to show how layered this system really is. In a 2012 study, Zilioli and Watson found that a man's baseline cortisol and baseline testosterone together predicted how much his testosterone rose after a social victory (Zilioli & Watson, 2012). In plain terms, a stressed-out man with chronically high cortisol doesn't get the same hormonal reward from winning. His own stress chemistry mutes the payoff. I think about that finding constantly when a patient tells me he's grinding through eighty-hour weeks and wondering why nothing feels satisfying anymore.

There's a nuance here that the research has teased out beautifully. The testosterone response to competition isn't automatic. It depends on how much the contest matters to you. A 2020 study of soccer players by Manuel Jiménez and colleagues found that both the seriousness of the competition and the level of play modulated how much testosterone and cortisol the athletes produced (Jiménez et al., 2020). A meaningless scrimmage barely moved the needle. A match that counted lit them up. Your body is reading the stakes, and it's allocating hormonal resources accordingly. Think about what that means for a man whose baseline testosterone is already low. The fuel that's supposed to surge when something matters just isn't there in the tank.

When the Loop Runs in Reverse

This is the part I see play out in my exam room more than any textbook describes. Low testosterone doesn't usually announce itself with a single dramatic symptom. It creeps. A man in his forties starts declining the things that used to give him those little wins. He stops competing. He stops initiating. He avoids the gym because progress feels impossible, avoids the hard conversation at work because he doesn't have the fight in him, avoids intimacy because the spark went quiet. And every avoided challenge is a win he doesn't get, which means a testosterone bump he doesn't get, which makes the next challenge feel even bigger.

You can see how the winner effect, running in reverse, becomes a confidence death spiral. The hormone drops, the behavior shrinks, and the shrinking behavior drops the hormone further. By the time a man sits across from me, he often blames himself. He thinks he's gotten lazy or soft or old. What I tell my patients is that biology is frequently writing the script they're reading as a character flaw.

And the symptoms are real and measurable, not vibes. The clinical literature is clear that genuine testosterone deficiency drags down mood, vitality, and cognition alongside the physical stuff. A 2024 review by Mathis Grossmann in Current Opinion in Endocrinology, Diabetes and Obesity summarized three large randomized controlled trials and laid out where the evidence is strongest, including effects on vitality, mood, and sexual function in men with confirmed low testosterone (Grossmann, 2024). That last point matters: the benefits are most reliable in men who actually have a deficiency, which is exactly why we test before we treat.

Can You Restart the Engine?

Here's the honest answer, and it's the one I give every man who walks into the clinic hoping testosterone is a magic switch. It isn't. But it's also not nothing, and the distinction matters.

If your testosterone is genuinely low (confirmed on more than one early-morning blood draw, paired with real symptoms), restoring it to a healthy range can absolutely help you climb back into that winner's loop. When the fuel is back in the tank, the surge that's supposed to come when something matters can actually happen. Men describe it less as becoming a different person and more as becoming themselves again. The willingness to engage comes back. They start saying yes to challenges instead of quietly ducking them. And once they string a few wins together, the biology starts reinforcing the behavior the way it's designed to.

But (and this is a big but) testosterone replacement is a tool, not a personality transplant. I've watched men expect a vial to fix a marriage, a career, and twenty years of avoided gym sessions all at once. That's not how it works. What testosterone replacement therapy can do is remove a biological brake. It gives you back the raw material so that when you do the hard things, your body responds the way it should. The hard things are still on you.

I also push back on guys who want to chase supraphysiologic levels because they think more is more. It isn't. Confidence isn't linear with your testosterone number, and pushing levels into the stratosphere buys you side effects, not superpowers. The goal is a healthy, well-monitored range, with regular labs to keep an eye on your hematocrit, your estrogen, and your prostate markers. If a clinic is handing out testosterone without that monitoring, run the other way. If you want a deeper walkthrough of what proper care looks like, our team put together a guide for men over 30 considering TRT that covers the labs, the timeline, and the honest tradeoffs.

Building Your Own Winner Effect, With or Without TRT

Whether or not you ever need treatment, you can work the winner effect on purpose. The research suggests the loop responds to meaningful wins, so stack the deck in your favor. Pick challenges that matter to you, then make them small enough that you actually finish them. Three sets you complete beat a heroic workout you skip. A short, honest conversation you actually have beats the big confrontation you keep postponing.

Sleep, strength training, and managing your stress all feed into this too, because cortisol (your stress hormone) tends to blunt the testosterone response when it's chronically elevated. A man who's running on four hours of sleep and a constant drip of work anxiety is fighting his own chemistry. The Texas summer's brutal stretch makes the gym easy to skip, I get it, but consistency in even modest training is one of the most reliable ways to keep this system humming.

And if you've done all of that and you still feel like the engine won't turn over, that's not a moral failing. That's a signal worth investigating. Sometimes willpower really is being undercut by physiology, and the only way to know is to look.

The winner effect is a reminder that confidence isn't purely a mindset you talk yourself into. It's a biological conversation between your behavior and your hormones, one that can be nurtured and, when it's broken, often repaired. If you're a man in the Southlake area who feels like that conversation has gone quiet, getting your levels checked is a reasonable first step. At Magnolia Functional Wellness, we'd rather show you the data and have an honest talk about whether your biology is holding you back than let you keep blaming yourself for something a blood test might explain.

By Dr. Farhan Abdullah, DO | Medical Director, Magnolia Functional Wellness | Southlake, TX