Watching UFC back in the day it made surface level sense that fighters would be shredded and have great physiques as they're professional athletes. However, upon learning about cortisol and its effects on the body, I became curious as to how these MMA fighters' physiques — who are subject to insane levels of physiological and psychological stress — can rival bodybuilders. Here's what I found, and what we can learn from them:
I. The Relationship Between Stress and Fat
Walk into any corporate office and you'll see it everywhere: the stressed manager built like a milk bag, the overworked consultant reaching for her coffee, the executive whose body composition needs to be studied.
The science is always the same. Chronic stress floods your system with cortisol. Cortisol breaks down muscle, stores fat around your midsection, cranks up your appetite for garbage food, and turns your metabolism into trash. It's why stress belly eating and bloating is a real phenomenon, and why your coworker took the bulk too far during Q4.
The science speaks for itself. Cortisol is the enemy of the physique you want.
That's what I thought until I looked towards the world of mixed martial arts.
UFC fighters live in a state of stress that would hospitalize most of us. They train 6-8 hours daily, knowing that one bad day could end their career. They cut weight to dangerous extremes. They step into a cage where a mistake means getting choked unconscious or knocked out cold, often in front of millions of viewers.
The psychological pressure is unimaginable. Your boss giving you a hard time at work? Try having another man trying to knock you out cold while your paycheck and your family's welfare is relying on you to strangle him.
Yet walk through the UFC Performance Institute, and you'll see physiques that rival bodybuilders and are straight out of a magazine. We're talking about trained killers with 6-8% body fat who look like they were designed to represent peak human physical condition.
II. The Paradox Presented
How is this possible?
Here's where nuance gets involved:
For most of the general population, we experience around the clock stress: constant, grinding, with no clear endpoint. It's a steady drip of cortisol that slowly floods your system. Add on top of that being indoors under biologically confusing blue lights, and you have an environment that our bodies did not evolve to thrive in... much less deal with on a daily basis.
Fighter stress is akin to the hunting lion. Explosive, intense hunting followed by hours of blissful recovery in the shade. Their stress comes in intense waves, but then it's over. Complete recovery. Reset. Repeat.
This intermittent stress pattern triggers something called hormesis – the biological phenomenon where small doses of stress actually make you stronger. It's the same principle behind vaccines or cold showers. What doesn't kill you literally makes you stronger, but only if it comes in the right dose and frequency.
III. Working With Biology
Here's where working with your biology gets worthwhile. While cortisol is spiking during training and fights, something else is happening: testosterone and growth hormone are going through the roof.
Intense training, especially the kind that simulates life-or-death scenarios, triggers massive releases of anabolic hormones. These directly counteract cortisol's muscle-wasting effects. It's like having your foot on the gas and brake at the same time, but somehow still accelerating. These fighters aren't training like the bodybuilders they resemble. While gym-goers focus on bicep curls and chest flies, they're throwing medicine balls at max velocity and doing landmine punches. They're doing explosive, rotational movements that recruit their entire body as one system. Yet despite training in ways that seem counterintuitive to muscle building, they develop some of the most impressive physiques in sports.
IV. The Hormonal Aspect
The fighters' bodies become home to many hormonal processes, with cortisol playing just one part in a complex relationship that includes:
- Growth hormone spikes from intense training
- Testosterone elevation from competition and resistance work
- Improved insulin sensitivity from the physical demands
- Enhanced recovery hormones during structured rest periods
V. Max Effort Recovery
Modern fighters also have something previous generations didn't: the science of recovery.
While old-school fighters lived by "more is better" – train until you puke, then train some more – today's elite athletes take recovery VERY seriously. Don't get me wrong, fighters were absolute animals then, and there is merit in that style, but some fighters could've seriously prolonged/improved their careers with improved technology and recovery practices (I think of people like Cain Velasquez, BJ Penn, Chuck Liddell, etc...). Now, fighters track their sleep, have premade meals timed to optimize recovery, and use ice baths, saunas, massage, and meditation to name a few.
Now when it comes to talking about physique, I would be remiss to not mention genetics.
VI. BUT WHAT ABOUT GENETICS???
For every shredded fighter you see on TV, thousands more gave it up because their bodies couldn't handle the stress load.
This is crucial to understand: UFC fighters aren't extra-terrestrial. They represent the genetic lottery winners of stress resilience. The sport is brutally efficient at filtering for genetic freaks; people whose stress response systems are outliers and are literally built for the sport.
Think of it like this: if you randomly selected 1,000 people and put them through UFC training, maybe 50 would complete the program. Of those 50, maybe 10 would maintain elite physiques under the stress. Of those 10, maybe 2 would have the psychological makeup to perform under the bright lights. We're not seeing normal humans who learned to handle stress. We're seeing statistical outliers who were built for this specific type of challenge.
VII. What This Means for the Rest of Us
So what can regular humans learn from these stress-adapted warriors?
The pattern matters more than the intensity — Your body might handle intense bursts of stress better than moderate chronic stress. That brutal workout followed by complete rest could be superior to months of grinding through low-level anxiety.
Recovery isn't optional — The fighters' secret weapon isn't just their ability to handle stress, it's their obsession with recovering from it. Sleep, nutrition, and downtime aren't luxuries; they're essential for peak performance.
Physical stress beats psychological stress — Your body has evolved sophisticated systems for handling physical threats and challenges. Psychological stressors (ex: deadlines, social media, work anxiety) hijack these systems without providing the physical outlet they were designed for.
Context is everything — Stress with a purpose, an endpoint, and a recovery plan is fundamentally different from stress that feels endless and meaningless.
VIII. The Anthropological Approach
Perhaps most importantly, UFC fighters have recreated something our ancestors lived with for millennia: intermittent high-intensity stress followed by genuine recovery periods. Who would've guessed that such a historic sport would have ancestral patterns??
Our stress response systems evolved for escaping predators and hunting mammoths, not for checking emails at 11 PM and worrying about quarterly reports. Fighters train the exact systems our stress hormones evolved to support, then give those systems time to reset. Modern life constantly hits us with stress responses that outweigh the outlets.
IX. The Fighter's Formula
For my math people, I have simplified it into a formula:
(Intense Stress + Physical Outlet + Complete Recovery) × Repetition = Adaptation
Remove any element, and the system breaks down. Acute stress without recovery becomes chronic and debilitating. Physical stress without mental resilience leads to burnout. Recovery without preceding stress leads to weakness. Passion is also noteworthy to be included in this formula.
X. Ok So How Do I Get Jacked?
You don't need to step into a cage to apply these lessons. You can create your own version of intermittent stress followed by structured recovery. Sprint intervals instead of endless jogging. Challenging projects with clear deadlines instead of perpetual busy work. Cold showers followed by warm comfort instead of constant temperature comfort.
The goal isn't to eliminate stress but rather to make stress work for you instead of against you. Working with our hard-wired biology.
UFC fighters have, intentionally or not, taken advantage of something fundamental about human physiology. They've shown us that under the right conditions, stress can build you up instead of breaking you down.
The question isn't whether you can handle stress of a UFC fighter.
The question is whether you can learn to handle the stress like one.
- Alex, PrimalSol.