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Type II allostatic overload
Also known as: Type I allostatic overload, Type II allostatic overload, Type 2 allostatic overload
Facts (25)
Sources
Allostasis revisited: A perception, variation, and risk framework frontiersin.org Sep 28, 2022 17 facts
claimHomeostatic overload is most analogous to Type 2 allostatic overload, where prolonged high hormone levels are damaging but an Emergency Life History Stage (ELHS) is not triggered.
claimIn the energetics-based framework for allostatic load, Type II allostatic overload occurs when allostatic load remains high without exceeding basal energy available, resulting in pathology associated with chronically elevated glucocorticoids.
claimThe distinction between Type I and Type II allostatic overload is that Type I involves responding directly to physiological starvation (actual Potential Reproductive Potential = 0), whereas Type II involves responding to an alternative predictor of impending negative energy balance that may or may not accurately reflect low Potential Reproductive Potential.
referenceHomeostatic overload is analogous to the 'level C' regulatory range described in Landys et al. (2006) and is most similar to Type 2 allostatic overload, where prolonged high hormone levels are damaging but an Emergency Life History Stage (ELHS) is not triggered.
referenceWada (2019) suggests that thresholds defined by damage, such as Type II allostatic and homeostatic overload, are difficult to pinpoint because damage accumulation and repair mechanisms are involved.
claimType II allostatic overload results in pathology associated with chronically elevated glucocorticoids, where basal energy availability is defined by Eg (food available in the environment) and Ecr (which includes Eg, endogenous energy reserves, and access to Eg based on factors like predation risk and social status).
claimThe cost of surrendering a physical location includes losing fitness-related investments from the normal life-history stage and increasing the risk of damage from Type II/allostatic overload.
claimThe cost of activating the Emergency Life History Stage (ELHS) includes surrendering fitness-related investments associated with a normal life-history stage and potentially increasing the risk of damage associated with Type II/allostatic overload.
claimIn Type I allostatic overload, the threshold is an allostatic shift that activates the Extreme Life History Strategy (ELHS), making both the nature of the threshold and its ultimate function clear.
claimIn the McEwen and Wingfield (2003) model, Type II allostatic overload occurs when allostatic load remains high without exceeding basal energy available, where basal energy is defined as Eg (food available in the environment) and Ecr (endogenous energy reserves and access to Eg).
claimType II allostatic and homeostatic overload thresholds are difficult to pinpoint because they involve complex interactions between damage accumulation and repair mechanisms, as noted by Wada (2019).
claimAs climate change causes shifts in habitats globally, highly responsive individuals and groups may become more vulnerable to Type II allostatic overload.
claimIn the energetics-based framework by McEwen and Wingfield (2003), Type I allostatic overload occurs when allostatic load exceeds the energetic resources available in the environment, while Type II allostatic overload occurs when allostatic load remains high without exceeding basal energy available.
claimType I allostatic overload is distinct from negative energy balance, as animals can routinely burn fat reserves (e.g., during the night) without entering allostatic overload, as noted by Hatchwell et al. (2009).
claimType II allostatic overload results in pathology associated with chronically elevated glucocorticoids.
claimType II allostatic overload is most likely to occur in humans and captive animals because they live in environments where resource availability is disconnected from historically relevant cues.
claimType II allostatic overload is considered to be rare in wild animal populations.
Understanding Allostasis: Stability Through Change - Cannelevate cannelevate.com.au Jan 2, 2026 8 facts
claimType 2 allostatic overload is relevant to modern chronic stress situations, including low socioeconomic status, chronic discrimination, poor working conditions, or social isolation.
claimStructural and systemic interventions, such as improving socioeconomic conditions, reducing health inequalities, enhancing neighbourhood safety, improving healthcare access, implementing workplace stress reduction programmes, and strengthening community support networks, are necessary to tackle the social determinants that drive Type 2 allostatic overload.
claimType 2 allostatic overload can only be counteracted through learning, behavioural change, or social transformation, as it lacks a natural escape mechanism.
claimStructural and systemic interventions, such as improving socioeconomic conditions, reducing health inequalities, enhancing neighbourhood safety, improving healthcare access, implementing workplace stress reduction programmes, and strengthening community support networks, are necessary to address Type 2 allostatic overload.
claimType 2 allostatic overload occurs with sufficient or excess energy consumption accompanied by social conflict or dysfunction, involving chronic elevation of stress mediators without escape response activation.
claimType 2 allostatic overload is characterized by elevated thyroid hormone (T3) levels and can only be counteracted through learning, behavioral change, or social transformation.
referenceMcEwen and Wingfield identified two distinct types of allostatic overload: Type 1, which occurs when energy demand exceeds available energy supply, and Type 2, which occurs with sufficient or excess energy consumption accompanied by social conflict or dysfunction.
claimType 2 allostatic overload involves chronic elevation of stress mediators without escape response activation, is characterized by elevated thyroid hormone (T3) levels, and is associated with social conflict, dysfunction, and modern chronic stress situations.