The Sensitization Threshold: why your body stopped responding

What the threshold is

Every body carries a buffer, a reserve of capacity that absorbs the daily demands of living. Stress, a poor night’s sleep, an infection, a stretch of bad food, the body adapts and recalibrates. While that buffer holds, you stay forgiving. You recover from setbacks. Inputs produce predictable outputs, and life feels manageable even when it is busy.

But the buffer is not infinite. When the regulatory systems that maintain it are under sustained load, the buffer declines. And once it declines far enough, something fundamental changes. I call that change the Sensitization Threshold.

It is the point at which cumulative load exceeds what your body can tolerate. The tipping point where normal inputs begin producing abnormal outputs. The research community describes a closely related idea, allostatic load, the cumulative wear on the body’s regulatory systems when they are forced to adapt to chronic stress.¹ Bruce McEwen’s work at Rockefeller University established the framework: the body adapts until it cannot, and the cost of that adaptation accumulates silently until the system tips.¹² What I see in clinic is the human version of that tipping point, the moment the patient notices that something has changed and cannot put it back.

What it looks like

Before the threshold is crossed, the body compensates. After it is crossed, the same inputs produce different outputs, and the change is unmistakable once you know what you are looking at.

Fatigue persists despite adequate sleep. Weight plateaus despite careful restriction. Gut symptoms continue despite elimination diets. Inflammation stays elevated despite supplementation. Hormones remain chaotic despite targeted intervention. Good days appear and then vanish without explanation, so you can never quite trust a good week to hold.

From the outside it looks like a collection of unrelated problems arriving at once, which is exactly why people get passed between specialists who each see only their own piece. From the inside it is one thing. The body stopped responding predictably. It has not become lazy and it has not turned against you. It has become sensitised. Small inputs now trigger exaggerated responses, because the system is operating without a buffer.³ A meal that should be neutral causes a flare. A workout that should build you up breaks you down. A stressful day that you would once have shrugged off now costs you a week.

What pushes people over

The threshold is rarely crossed by one thing. It is the accumulation, the slow spending of a buffer over years. But there is usually a final stressor, the one too many, that tips a system already running close to the edge. Recognising that moment is often the first step in understanding the whole picture.

In my patients the common triggers are a viral infection, including the lingering effects of COVID, a long stretch of chronic stress from work or caregiving, a hidden dental or root canal infection, severe restriction dieting or over-exercise, a major hormonal shift such as pregnancy loss or menopause,⁵ steroid exposure, or an environmental trigger like mould. James’s collapse followed three years of sixty-hour weeks, newborn twins, chronic sleep deprivation, and then a root canal infection that pushed an already-spent system into crisis. Claire’s methylation went offline after a third pregnancy loss layered onto chronic stress.⁶ Rachel’s whole family declined within months of moving into a water-damaged, mould-affected house.⁴ None of these stressors would tip a body with a full buffer. They tipped a body whose buffer was already gone.

Why adding more does not work

This is the part that matters most, because it is the opposite of what almost everyone tries. Once the threshold is crossed, adding more inputs does not help. Stacking another supplement, another elimination, another protocol onto a sensitised system increases the instability rather than reducing it. The system has lost its capacity to process inputs predictably, so more inputs create more chaos, not more clarity. Input optimisation is not the same thing as regulatory stabilisation, and confusing the two is why protocol fatigue is so common in people who have been unwell for years.

The way back is not more. It is less, then order. Stop stacking. Reduce the cumulative load. Restore the basics first, sleep, blood sugar, nervous system regulation, the foundations that rebuild the buffer. Then map which systems are actually offline and rebuild them in sequence, using the Healing Hierarchy. Stability comes before progress. Restore the stability and effort starts working again, often using the very interventions that failed when they were thrown at a system that could not yet use them.

How to tell where you sit

The Stability Score is a simple zero to ten measure of how predictable and resilient your body has become. It is the clearest way to tell whether you are operating below your threshold or beyond it. A low score means you are sensitised and the priority is stabilisation, not optimisation. A higher score means the buffer is rebuilding and you can begin to push. It gives you a starting position and a number to move, rather than a vague sense of how you feel on the day.

The way back

Crossing the threshold is reversible. The body that became sensitised can become resilient again, because the buffer can be rebuilt. The path is not dramatic and it is not fast, but it is reliable: lower the load, restore the foundations, then work through the systems in order, confirmed by data, so each step holds before you build on it. Most of my patients recognise themselves somewhere between a two and a five on the Stability Score when they start. That is not a verdict. It is a starting position, and the entire point of the framework is to move that number upward in a way that lasts.

Where to start

If this describes you, the most important shift is to stop adding and start mapping. My book lays out exactly how, the threshold, the testing, and the sequence that rebuilds the buffer.

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