The Cost of Doing Business
An Simple Introduction to Allostatic Load
Stress Load
The experience of stress is no mystery to anybody who's been alive for a while. Stress is a natural and necessary part of human existence. Despite the fact that popular health science often demonizes this force of nature into something that should be thwarted, the truth is more nuanced.
We need stress to change, evolve, and grow. The adaptations that occur over time, however, are not free. Your body seeks to stabilize its functional parameters constantly. It learns the boundaries based on normative physiological set points, but also learns how to respond based on your genetics, personal history, and environmental inputs.
The cost of stabilizing your physiology (this is called load, a concept we'll discuss later) can be insidious because it accumulates slowly over time. Often, the chronic buildup of adapting to stress slips under the radar until we reach a critical point of failure. For example, chronic stress load is a major contributor to cardiovascular disease.
Allostatic load is the scientific term used to describe the cost of doing business in the business of life. While allostatic load is not by any means a novel concept, what is novel is putting it into practical terms for those seeking to manage their stress load in a way that allows for meaningful changes in output.
Wearable devices that help track allostatic load are common in the health marketplace these days, but to be honest, they are often marketed disingenuously, which can lead to a misappropriation of this resource—even among those who are supposed to be well informed about these matters.
My goal for this article is to present to you what allostatic load is and how to manage it. I want to help you better understand the underlying complexities of stress and use relevant and actionable language to do so. Hopefully, this short article can do justice to this vast topic and set you on a path to improving your relationship with stress, with some tangible takeaways to help yourself and those around you.
What Is Stress, Really?
Stress is a normal, natural part of life. In fact, growth and change are impossible without it. Understanding the basics of stress and how we respond to it is important for feeling and performing your best.
Hans Selye, the grandfather of stress research, outlined a nonspecific response to stress called the General Adaptation Syndrome (GAS). The three phases of GAS are Alarm—increased arousal of the autonomic nervous system, Resistance—the effort to maintain performance under stress, and Exhaustion—where performance or function breaks down. While Selye's model doesn’t capture everything we now understand about stress, it helps illustrate the general effects of stress on physiology.
Stress doesn't just live at the extremes in moments of acute irritation. We don't just toggle between fight/flight and rest/digest. Since we are experiencing some level of stress constantly—whether it's purposeful, like the accumulated cost from regular exercise, or ambient, like that from a demanding career—the costs accrue over time.
The collective effects of these inputs are interacting with each other and our physiology all of the time. To maintain system normalcy, the autonomic nervous system and the hypothalamic-pituitary-adrenal axis (HPA axis) work together to respond to the ever-changing demands of the environment. The amount of energy it takes to keep adapting is what we refer to as load.
Allostasis, or "stability through change," is how the body adjusts to the aggregation of stressful inputs—not just in the moment, but over time. Importantly, this is characteristic of a complex adaptive dynamical system (CADS; MacMillan) — a system composed of many interacting components that continuously adjust in response to internal and external changes. Your body, like any CADS, is nonlinear, meaning small inputs can sometimes cause big changes, and big inputs may not cause any visible response until a critical threshold is reached.
Acute stress, with sufficient opportunity and resources to recover (i.e., return to baseline), can result in a higher level of resilience and adaptability. Insufficiencies—whether in opportunity or resources—especially over the long term, lead to allostatic overload. This doesn't necessarily mean the system fails to adapt. It always will adapt. But the body begins to borrow from other systems to keep going—it goes into debt.
While the basic idea of allostatic load is straightforward, dealing with the massive complexity of how all the biological factors of the human system interact with ever-shifting environmental demands is not. This is where the lens of complex adaptive systems becomes useful. The human stress response cannot be fully understood through linear cause-and-effect logic alone; it is shaped by emergent properties, feedback loops, and phase transitions — spontaneous reorganizations that occur when the system crosses a threshold of accumulated input.
Each of us is a bit of a unique snowflake in how we respond to allostatic load. That uniqueness emerges from how our biological systems adapt over time, shaped by dynamic patterns of learning, feedback, and resource allocation. These adaptations don’t occur in a vacuum — they emerge from the interplay of history, environment, behavior, and physiology in ways consistent with complex systems behavior.
One important point that's often missed is how hard it is to identify linear causes in our stress response. For example, “I got a bad night or two of sleep, and then I got sick.” While this might sound logical, that kind of cause-and-effect thinking oversimplifies how stress works and often prevents us from seeing the bigger picture of stress load management.
Monitoring the Cost of Adaptation
If you think of your allostatic load in terms of a balance sheet for a business, you'd keep track of both income and expenses.
HRV (heart rate variability) can serve as your daily bank balance. When HRV is high, it generally reflects greater parasympathetic activity and adaptability. When HRV is consistently low, it's a sign that your system is under strain and potentially failing to recover. It's a snapshot of your system’s liquidity, so to speak.
Other metrics can help too: resting heart rate, sleep latency, energy trends, mood, motivation. These are the numbers on the spreadsheet, but context still matters more than raw data.
Wearables are one way to keep tabs, but they’re not the whole story. They can be helpful tools—if you understand what you’re measuring and why.
Managing Load
Stress is inevitable. Your job is to manage it well. Think in terms of deposits and withdrawals.
Withdrawals include poor sleep, emotional stress, under-fueling, overtraining, inflammation, and hyperstimulation.
Deposits include nutrient-dense food, sleep, connection, time outdoors, breathwork, parasympathetic input, and purpose.
This isn’t about perfection. It’s about probability and pacing—supporting your system when you can, so it has the capacity to support you when it must.
Special Considerations: Tactical, Shift Work, Emergency Medicine
For those in tactical professions, healthcare, and emergency medicine, allostatic overload is common. These environments demand consistent performance under high stress, often without adequate time or space for recovery.
Tactical athletes often operate in states of hypervigilance, training hard while navigating sleep deprivation, trauma exposure, and operational unpredictability. Over time, even well-trained systems can fall into depletion if recovery doesn’t match the output.
Shift workers—especially those in rotating or overnight schedules—battle circadian misalignment. This has downstream effects on hormonal rhythms, immune resilience, and cognitive function. Managing light exposure, sleep hygiene, and nutrient timing becomes critical.
Emergency responders deal with both acute and cumulative trauma. The body adapts, but often by suppressing warning signals. Long-term, this can show up as immune dysfunction, emotional dysregulation, or burnout.
In these roles, managing load isn’t just personal—it’s professional. Organizations should structure recovery into culture. And individuals in these spaces deserve a framework that helps them sustain their capability over time.
Accounting for Stress
Understanding allostatic load matters because it tells you where you stand. It shows you whether your body is coping, adapting, or slipping into depletion. And it helps you see beyond simple cause and effect toward a deeper systems view of how you’re operating.
Stress isn't the enemy. It's the cost of living and engaging with the world. But like any cost, it needs to be accounted for.
So ask yourself:
Are you withdrawing more than you’re depositing?
Are you paying interest on your stress, or compounding resilience?
Start small.
Assess. Where do I stand now and what needs attention?
Monitor. How are things changing?
Probe. Try small experiment and see what hurts and what helps.
And remember—resilience isn't a trait. It's a capacity. And capacity can be trained.
Thanks for reading,
Rob
References
Hans Selye – The Stress of Life
McEwen BS – Protective and Damaging Effects of Stress Mediators (Allostatic Load model)
Juster RP, McEwen BS, Lupien SJ – Allostatic load biomarkers of chronic stress and impact on health and cognition
Bessel van der Kolk – The Body Keeps the Score
Robert Sapolsky – Why Zebras Don’t Get Ulcers
Hey, Rob. Great read. Thanks for posting. I heard you recently on Jocko and enjoyed the content.