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Chapter eight: Fasting
Glossary
Endogenous body reserves: Internal tissues that are broken down (catabolized) by an animal as fuel when energetic expenditures are greater than energy intake.
Fasting: Voluntary cessation of food intake.
Glucocorticoids: A group of steroid hormones that are important in carbohydrate, lipid,
and protein metabolism, as well as immune and stress responses. In marine mammals, the prominent glucocorticoid is cortisol.
Gluconeogenesis: The process of manufacturing the required fuel glucose from the noncarbohydrate precursors glycerol (from triacylglycerols) and amino acids (derived
from proteins). Gluconeogenesis occurs mainly in the liver and kidneys.
Hormones: Chemical messengers that are produced in the body that control and regulate
the activity of certain cells or organs. This includes hormones that affect appetite
(leptin, ghrelin), growth (growth hormone [GH], insulin-like growth factor 1 [IGF-1]),
and metabolism (thyroid hormones, T3 and T4).
Ketone bodies: Carbon structures that derive from oxidized fatty acids and are manufactured in the liver, which can be used as a fuel source during fasting.
Resting Metabolic Rate (RMR): A measure of energy expenditure reflecting the total
energy requirements of an inactive animal within its thermoneutral zone.
Triacylglycerols: A high-energy lipid source derived from glycerol and three fatty acids.
It is the primary lipid in the blubber layer of marine mammals and can be broken
down via lipolysis into glycerol and free fatty acids (FFA).
References
Adams, S.H. and D.P. Costa. 1993. Water conservation and protein metabolism in northern elephant
seal pups during the postweaning fast. Journal of Comparative Physiology B 163:367–373.
Aksenov, A.A., L. Yeates, A. Pasamontes et al. 2014. Metabolite content profiling of bottlenose dolphin exhaled breath. Analytical Chemistry 86:10616–10624.
Aoki, K., Y.Y. Watanabe, D.E. Crocker et al. 2011. Northern elephant seals adjust gliding and stroking patterns with changes in buoyancy: Validation of at-sea metrics of body density. Journal of
Experimental Biology 214(17):2973–2987.
Arnould, J.P.Y, J.A. Green, and D.R. Rawlins. 2001. Fasting metabolism in Antarctic fur seal
(Arctocephalus gazella) pups. Comparative Biochemistry and Physiology A 129:829–841.
Beauplet, G., C. Guinet, and J.P.Y. Arnould. 2003. Body composition changes, metabolic fuel use, and
energy expenditure during extended fasting in subantarctic fur seal (Arctocephalus tropicalis)
pups at Amsterdam Island. Physiological and Biochemical Zoology 76(2):262–270.
Bennett, K.A., B.J. McConnell, S.E. Moss, J.R. Speakman, P.P. Pomeroy, and M.A. Fedak. 2010. Effects
of age and body mass on development of diving capabilities of gray seal pups: Costs and benefits of the postweaning fast. Physiological and Biochemical Zoology 83(6):911–923.
Bentley, P.J. 1963. Composition of the urine of the fasting humpback whale (Megaptera nodosa).
Comparative Biochemistry and Physiology 10(3):257–259.
Boily, P. and D.M. Lavigne. 1995. Resting metabolic rates and respiratory quotients of gray seals
(Halichoerus grypus) in relation to time of day and duration of food deprivation. Physiological
Zoology 68(6):1181–1193.
Bowen, W.D., D.J. Boness, and O.T. Oftedal. 1987. Mass transfer from mother to pup and subsequent mass
loss by the weaned pup in the hooded seal, Cystophora cristata. Canadian Journal of Zoology 65(1):1–8.
Boyd, I.L. 1991. Environmental and physiological factors controlling the reproductive cycles of pinnipeds. Canadian Journal of Zoology 69(5):1135–1148.
Burns, J.M., K. Lestyk, D. Freistroffer, and M.O. Hammill. 2014. Preparing muscles for diving: Agerelated changes in muscle metabolic profiles in harp (Pagophilus groenlandicus) and hooded
(Cystophora cristata) seals. Physiological and Biochemical Zoology 88(2):167–182.
Chapter eight: Fasting
Glossary
Endogenous body reserves: Internal tissues that are broken down (catabolized) by an animal as fuel when energetic expenditures are greater than energy intake.
Fasting: Voluntary cessation of food intake.
Glucocorticoids: A group of steroid hormones that are important in carbohydrate, lipid,
and protein metabolism, as well as immune and stress responses. In marine mammals, the prominent glucocorticoid is cortisol.
Gluconeogenesis: The process of manufacturing the required fuel glucose from the noncarbohydrate precursors glycerol (from triacylglycerols) and amino acids (derived
from proteins). Gluconeogenesis occurs mainly in the liver and kidneys.
Hormones: Chemical messengers that are produced in the body that control and regulate
the activity of certain cells or organs. This includes hormones that affect appetite
(leptin, ghrelin), growth (growth hormone [GH], insulin-like growth factor 1 [IGF-1]),
and metabolism (thyroid hormones, T3 and T4).
Ketone bodies: Carbon structures that derive from oxidized fatty acids and are manufactured in the liver, which can be used as a fuel source during fasting.
Resting Metabolic Rate (RMR): A measure of energy expenditure reflecting the total
energy requirements of an inactive animal within its thermoneutral zone.
Triacylglycerols: A high-energy lipid source derived from glycerol and three fatty acids.
It is the primary lipid in the blubber layer of marine mammals and can be broken
down via lipolysis into glycerol and free fatty acids (FFA).
References
Adams, S.H. and D.P. Costa. 1993. Water conservation and protein metabolism in northern elephant
seal pups during the postweaning fast. Journal of Comparative Physiology B 163:367–373.
Aksenov, A.A., L. Yeates, A. Pasamontes et al. 2014. Metabolite content profiling of bottlenose dolphin exhaled breath. Analytical Chemistry 86:10616–10624.
Aoki, K., Y.Y. Watanabe, D.E. Crocker et al. 2011. Northern elephant seals adjust gliding and stroking patterns with changes in buoyancy: Validation of at-sea metrics of body density. Journal of
Experimental Biology 214(17):2973–2987.
Arnould, J.P.Y, J.A. Green, and D.R. Rawlins. 2001. Fasting metabolism in Antarctic fur seal
(Arctocephalus gazella) pups. Comparative Biochemistry and Physiology A 129:829–841.
Beauplet, G., C. Guinet, and J.P.Y. Arnould. 2003. Body composition changes, metabolic fuel use, and
energy expenditure during extended fasting in subantarctic fur seal (Arctocephalus tropicalis)
pups at Amsterdam Island. Physiological and Biochemical Zoology 76(2):262–270.
Bennett, K.A., B.J. McConnell, S.E. Moss, J.R. Speakman, P.P. Pomeroy, and M.A. Fedak. 2010. Effects
of age and body mass on development of diving capabilities of gray seal pups: Costs and benefits of the postweaning fast. Physiological and Biochemical Zoology 83(6):911–923.
Bentley, P.J. 1963. Composition of the urine of the fasting humpback whale (Megaptera nodosa).
Comparative Biochemistry and Physiology 10(3):257–259.
Boily, P. and D.M. Lavigne. 1995. Resting metabolic rates and respiratory quotients of gray seals
(Halichoerus grypus) in relation to time of day and duration of food deprivation. Physiological
Zoology 68(6):1181–1193.
Bowen, W.D., D.J. Boness, and O.T. Oftedal. 1987. Mass transfer from mother to pup and subsequent mass
loss by the weaned pup in the hooded seal, Cystophora cristata. Canadian Journal of Zoology 65(1):1–8.
Boyd, I.L. 1991. Environmental and physiological factors controlling the reproductive cycles of pinnipeds. Canadian Journal of Zoology 69(5):1135–1148.
Burns, J.M., K. Lestyk, D. Freistroffer, and M.O. Hammill. 2014. Preparing muscles for diving: Agerelated changes in muscle metabolic profiles in harp (Pagophilus groenlandicus) and hooded
(Cystophora cristata) seals. Physiological and Biochemical Zoology 88(2):167–182.