Energy homeostasis

In biology, energy homeostasis, or the homeostatic control of energy balance, is a biological process that involves the coordinated homeostatic regulation of food intake (energy inflow) and energy expenditure (energy outflow).^[1]^[2]^[3] The human brain, particularly the hypothalamus, plays a central role in regulating energy homeostasis and generating the sense of hunger by integrating a number of biochemical signals that transmit information about energy balance.^[2]^[3]^[4] Fifty percent of the energy from glucose metabolism is immediately converted to heat.^[5]

Energy homeostasis is an important aspect of bioenergetics.

^ Frayn KN (2013). "Chapter 11: Energy Balance and Body Weight Regulation". Metabolic Regulation: A Human Perspective (3rd ed.). John Wiley & Sons. pp. 329–349. ISBN 9781118685334. Retrieved 9 January 2017.
^ ^a ^b Malenka RC, Nestler EJ, Hyman SE (2009). Sydor A, Brown RY (ed.). Molecular Neuropharmacology: A Foundation for Clinical Neuroscience (2nd ed.). New York: McGraw-Hill Medical. pp. 179, 262–263. ISBN 9780071481274. Orexin neurons are regulated by peripheral mediators that carry information about energy balance, including glucose, leptin, and ghrelin. ... Accordingly, orexin plays a role in the regulation of energy homeostasis, reward, and perhaps more generally in emotion. ... The regulation of energy balance involves the exquisite coordination of food intake and energy expenditure. Experiments in the 1940s and 1950s showed that lesions of the lateral hypothalamus (LH) reduced food intake; hence, the normal role of this brain area is to stimulate feeding and decrease energy utilization. In contrast, lesions of the medial hypothalamus, especially the ventromedial nucleus (VMH) but also the PVN and dorsomedial hypothalamic nucleus (DMH), increased food intake; hence, the normal role of these regions is to suppress feeding and increase energy utilization. Yet discovery of the complex networks of neuropeptides and other neurotransmitters acting within the hypothalamus and other brain regions to regulate food intake and energy expenditure began in earnest in 1994 with the cloning of the leptin (ob, for obesity) gene. Indeed, there is now explosive interest in basic feeding mechanisms given the epidemic proportions of obesity in our society, and the increased toll of the eating disorders, anorexia nervosa and bulimia. Unfortunately, despite dramatic advances in the basic neurobiology of feeding, our understanding of the etiology of these conditions and our ability to intervene clinically remain limited.
^ ^a ^b Morton GJ, Meek TH, Schwartz MW (2014). "Neurobiology of food intake in health and disease". Nat. Rev. Neurosci. 15 (6): 367–378. doi:10.1038/nrn3745. PMC 4076116. PMID 24840801. However, in normal individuals, body weight and body fat content are typically quite stable over time^2,3 owing to a biological process termed 'energy homeostasis' that matches energy intake to expenditure over long periods of time. The energy homeostasis system comprises neurons in the mediobasal hypothalamus and other brain areas⁴ that are a part of a neurocircuit that regulates food intake in response to input from humoral signals that circulate at concentrations proportionate to body fat content^4-6. ... An emerging concept in the neurobiology of food intake is that neurocircuits exist that are normally inhibited, but when activated in response to emergent or stressful stimuli they can override the homeostatic control of energy balance. Understanding how these circuits interact with the energy homeostasis system is fundamental to understanding the control of food intake and may bear on the pathogenesis of disorders at both ends of the body weight spectrum.
^ Farr OM, Li CS, Mantzoros CS (2016). "Central nervous system regulation of eating: Insights from human brain imaging". Metab. Clin. Exp. 65 (5): 699–713. doi:10.1016/j.metabol.2016.02.002. PMC 4834455. PMID 27085777.
^ Kevin G. Murphy & Stephen R. Bloom (December 14, 2006). "Gut hormones and the regulation of energy homeostasis". Nature. 444 (7121): 854–859. Bibcode:2006Natur.444..854M. doi:10.1038/nature05484. PMID 17167473. S2CID 1120344.

[MetaReg2013-1] Frayn KN (2013). "Chapter 11: Energy Balance and Body Weight Regulation". Metabolic Regulation: A Human Perspective (3rd ed.). John Wiley & Sons. pp. 329–349. ISBN 9781118685334. Retrieved 9 January 2017.

[NHM-energy_balance-2] Malenka RC, Nestler EJ, Hyman SE (2009). Sydor A, Brown RY (ed.). Molecular Neuropharmacology: A Foundation for Clinical Neuroscience (2nd ed.). New York: McGraw-Hill Medical. pp. 179, 262–263. ISBN 9780071481274. Orexin neurons are regulated by peripheral mediators that carry information about energy balance, including glucose, leptin, and ghrelin. ... Accordingly, orexin plays a role in the regulation of energy homeostasis, reward, and perhaps more generally in emotion. ... The regulation of energy balance involves the exquisite coordination of food intake and energy expenditure. Experiments in the 1940s and 1950s showed that lesions of the lateral hypothalamus (LH) reduced food intake; hence, the normal role of this brain area is to stimulate feeding and decrease energy utilization. In contrast, lesions of the medial hypothalamus, especially the ventromedial nucleus (VMH) but also the PVN and dorsomedial hypothalamic nucleus (DMH), increased food intake; hence, the normal role of these regions is to suppress feeding and increase energy utilization. Yet discovery of the complex networks of neuropeptides and other neurotransmitters acting within the hypothalamus and other brain regions to regulate food intake and energy expenditure began in earnest in 1994 with the cloning of the leptin (ob, for obesity) gene. Indeed, there is now explosive interest in basic feeding mechanisms given the epidemic proportions of obesity in our society, and the increased toll of the eating disorders, anorexia nervosa and bulimia. Unfortunately, despite dramatic advances in the basic neurobiology of feeding, our understanding of the etiology of these conditions and our ability to intervene clinically remain limited.

[Homeostatic_control_of_energy_balance-3] Morton GJ, Meek TH, Schwartz MW (2014). "Neurobiology of food intake in health and disease". Nat. Rev. Neurosci. 15 (6): 367–378. doi:10.1038/nrn3745. PMC 4076116. PMID 24840801. However, in normal individuals, body weight and body fat content are typically quite stable over time^2,3 owing to a biological process termed 'energy homeostasis' that matches energy intake to expenditure over long periods of time. The energy homeostasis system comprises neurons in the mediobasal hypothalamus and other brain areas⁴ that are a part of a neurocircuit that regulates food intake in response to input from humoral signals that circulate at concentrations proportionate to body fat content^4-6. ... An emerging concept in the neurobiology of food intake is that neurocircuits exist that are normally inhibited, but when activated in response to emergent or stressful stimuli they can override the homeostatic control of energy balance. Understanding how these circuits interact with the energy homeostasis system is fundamental to understanding the control of food intake and may bear on the pathogenesis of disorders at both ends of the body weight spectrum.

[Hunger_-_CNS_energy_homeostasis-4] Farr OM, Li CS, Mantzoros CS (2016). "Central nervous system regulation of eating: Insights from human brain imaging". Metab. Clin. Exp. 65 (5): 699–713. doi:10.1016/j.metabol.2016.02.002. PMC 4834455. PMID 27085777.

[Nature2006KMSB-5] Kevin G. Murphy & Stephen R. Bloom (December 14, 2006). "Gut hormones and the regulation of energy homeostasis". Nature. 444 (7121): 854–859. Bibcode:2006Natur.444..854M. doi:10.1038/nature05484. PMID 17167473. S2CID 1120344.

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