A working definition through the Evolutionary Stress Framework (ESF) and the Biopsychosocial-Nutritional (BPSN) model.
The short version
Regulatory health is the ongoing capacity of a living system — a person, a body, a community — to maintain coherent function across changing conditions. It is not the absence of stress, illness, or load. It is the active, dynamic property of being able to absorb demand, recover from disruption, and adapt to context without losing internal coordination.
In the ESF, regulatory health replaces the traditional medical idea of health as a return to baseline. Health is not a state to be restored. It is an emergent property of fit — the moment-to-moment achievement of nervous systems, bodies, and environments working in coordinated exchange.
Core constructs
Emergent allostasis — Health as the ongoing emergent property of regulatory systems maintaining viability through predictive adjustment. Builds on Sterling’s allostasis but treats coherent regulation as something achieved across changing conditions rather than defended around a setpoint. Sterling and Eyer (1988); McEwen (1998); Sturmberg (2018).
Regulatory bandwidth — The coordinated adaptive range across interacting stress-responsive systems that determines whether perturbations can be absorbed without functional destabilization. Bandwidth varies by architecture, by state, and by cumulative load. Narrow bandwidth is not deficit; it is a different operating range with different costs and capacities. McEwen (2016); Picard and McEwen (2018); Hogenkamp (2026, in review).
Stress incoherence — The state in which long-standing regulatory calibrations become unsustainable under current environmental conditions. The systems are not broken; the fit has failed. Recovery comes through changing the conditions, not pathologizing the system. Hogenkamp, Sanghavi, and Natri (2026).
Co-regulation — Mutual adjustment between nervous systems that distributes regulatory load. It is reciprocal, not unilateral, and measurable through biobehavioral synchrony, heart-rate coupling, cortisol coordination, and autonomic state matching. Tronick (1989); Feldman (2007, 2017); Schore (2003); Porges-adjacent autonomic literature.
Fit — The alignment between a person’s regulatory architecture and the environment’s predictability, demands, and supports. The same biological system produces radically different outcomes depending on fit. The traits do not change; the fit does.
The BPSN extension
The Biopsychosocial-Nutritional (BPSN) model is the clinical-translation extension of ESF. It updates Engel’s (1977) biopsychosocial framework by adding the nutritional, metabolic, and microbial layer that current biology recognizes as foundational to regulation, prediction, and energy availability.
In the BPSN, regulatory health is supported across four coupled domains:
Biological networks — Mitochondrial, endocrine, immune, autonomic, and neurological systems regulate internal energy availability and physiological stability. McEwen and Stellar (1993); Picard and McEwen (2018).
Psychological systems — Appraisal, prediction, attention, and meaning-making transform uncertainty into action and modulate metabolic demand. Barrett (2017); Friston (2010).
Social structures — Access to safety, reciprocity, belonging, and shared labor regulates predictive and energetic load. Bolis, Balsters, and colleagues (2017, 2023); Crompton and colleagues on neurotype-matched interaction.
Nutritional, metabolic, and microbial systems — Substrate availability, gut-brain signaling, circadian alignment, and microbial ecology shape the energetic substrate on which all other regulation depends. Cryan and Dinan (2012); Mayer, Tillisch, and Gupta (2015); Picard, Juster, and McEwen (2014).
These four domains are not parallel “factors” acting on a person. They are coupled energy–information systems engaged in continuous exchange. Regulatory health is the emergent coherence of that exchange.
What this reframes
Health is not the absence of illness. It is the dynamic capacity to maintain coherent function under changing conditions. A person with chronic illness can have substantial regulatory health within their architecture. A person without diagnosed illness can have narrow regulatory bandwidth and be approaching incoherence.
Variation is architectural, not parametric. Different bodies and nervous systems are built differently, not turned up or down on a single scale. Regulatory health looks different across architectures; the benchmark is internal coherence and sustainable fit, not conformity to a population norm.
Co-regulation is biology. Relational accommodation, predictability, attunement, and connection are not “soft” supports added on top of medical care. They are the measurable substrate of regulatory health.
Intervention is environmental and energetic, not corrective. When fit fails, the work is to change the conditions — predictability, sensory environment, social attunement, nutritional substrate, circadian alignment, autonomy — so that the architecture can return to coherent function. The architecture is not what needs fixing.
Why the framing matters
Most current health systems are organized around deficit, deviation, and restoration to norm. Regulatory health asks a different question: what is this system trying to do, and what does it need to do it coherently?
That question travels across autism, ADHD, chronic illness, autoimmune conditions, mental health, aging, and the broader landscape of variation in human function. It does not require choosing between biological, psychological, social, or environmental explanations. It treats all four as coupled in a single dynamic.
For research, this means studying systems across time rather than averages across populations. For clinical practice, it means supporting bandwidth and fit rather than enforcing norms. For lived experience, it means that regulatory needs, accommodations, and relational supports are not extra — they are the work of being well.
The Evolutionary Stress Framework (ESF) and the Biopsychosocial-Nutritional (BPSN) model are conceptual frameworks developed at the Center for Adaptive Stress (CAS), an independent nonprofit conceptual systems research organization. ESF is a research lens, not medical advice. For the framework’s foundational publication, see Hogenkamp, Sanghavi, and Natri (2026), “Toward an Emergent Paradigm for Neurodiversity and Health,” Autism in Adulthood, DOI: 10.1177/25739581261433443. CAS publishes at evostress.blog and ndstress.org.