Knowledge Tree
negative energy balance
Facts (15)
Sources
Allostasis revisited: A perception, variation, and risk framework frontiersin.org Sep 28, 2022 15 facts
claimAllostatic overload Type 2 occurs when allostatic load is chronically high but the animal is not in a negative energy balance, and in this state, an emergency life-history stage (ELHS) is not triggered.
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.
claimResource availability is designated as Eg or cumulatively as Ecr in the revised allostasis model, which improves alignment with known responses to negative energy balance and accounts for individual variation in body reserves and resource access.
claimResource availability is designated as Eg or, cumulatively, Ecr. This designation improves alignment with known responses to negative energy balance and accounts for individual variation in body reserves and resource access, assuming more importance because the perception of this quantity is critical to estimating Perceived Resource Potential (PRP).
claimSome animals, such as those studied by Hatchwell et al. (2009), routinely burn fat during the night without entering Type I allostatic overload, contradicting the notion that allostatic overload is synonymous with negative energy balance.
claimStrategy 2 for endocrine response involves an animal maintaining glucocorticoid levels near a seasonal baseline until PRP is critically low, at which point only a negative energy balance results in a rise in glucocorticoid levels that trigger the ELHS.
claimAllostatic overload Type 1 occurs when an animal is in a state of negative energy balance, which is considered an undisputed signal of a threat to Potential Reproductive Potential (PRP).
formulaAllostatic overload Type 1 occurs when an animal is in a negative energy balance, specifically when the sum of all types of allostatic load exceeds resource availability (Eg).
claimIn Strategy 2 of endocrine response, an animal maintains glucocorticoid levels near a seasonal baseline until Potential Resource Predictability (PRP) is critically low, at which point only a negative energy balance triggers the Emergency Life History Stage (ELHS).
formulaResource availability (Eg) represents a limit to the energy an animal can expend without entering a negative energy balance and must be measured in the same units as allostatic load.
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).
claimNegative energy balance serves as a direct indication of exhausted Perturbation Resistance Potential (PRP) and is generally reliable, except during voluntary fasting such as during brooding.
claimThe most useful time interval for averaging energy expenditure to reflect allostatic load varies by species, sex, and season, based on the duration an animal can tolerate negative energy balance as part of its daily or seasonal routine.
claimAllostatic overload Type 2 occurs when an animal's allostatic load is chronically high, but the animal is not in a state of negative energy balance.
claimStrategy 2 for Emergency Life History Stage (ELHS) activation involves an animal maintaining glucocorticoid levels near a seasonal baseline until Potential Resource Availability (PRP) is critically low, at which point negative energy balance triggers a rise in glucocorticoids and ELHS activation.