A History of Modern Research into Fasting, Starvation, and Inanition

Lignot, Jean-Hervé; LeMaho, Yvon

doi:10.1007/978-3-642-29056-5_2

Cited by 15 publications

(18 citation statements)

References 117 publications

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“…Fasting animals undergo several stages defined by their metabolic substrate (Cherel, Robin & Le Maho, ; Belkhou et al., ; Castellini & Rea, ; Lignot & LeMaho, ). Early fasting is usually associated with heavy use of carbohydrates, as animals switch from the fed to the fasted state.…”

Section: Lipid Metabolism During Fastingmentioning

confidence: 99%

The physiology of lipid storage and use in reptiles

Price

2016

Biological Reviews

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Lipid metabolism is central to understanding whole-animal energetics. Reptiles store most excess energy in lipid form, mobilise those lipids when needed to meet energetic demands, and invest lipids in eggs to provide the primary source of energy to developing embryos. Here, I review the mechanisms by which non-avian reptiles store, transport, and use lipids. Many aspects of lipid absorption, transport, and storage appear to be similar to birds, including the hepatic synthesis of lipids from glucose substrates, the transport of triglycerides in lipoproteins, and the storage of lipids in adipose tissue, although adipose tissue in non-avian reptiles is usually concentrated in abdominal fat bodies or the tail. Seasonal changes in fat stores suggest that lipid storage is primarily for reproduction in most species, rather than for maintenance during aphagic periods. The effects of fasting on plasma lipid metabolites can differ from mammals and birds due to the ability of non-avian reptiles to reduce their metabolism drastically during extended fasts. The effect of fasting on levels of plasma ketones is species specific: β-hydroxybutyrate concentration may rise or fall during fasting. I also describe the process by which the bulk of lipids are deposited into oocytes during vitellogenesis. Although this process is sometimes ascribed to vitellogenin-based transport in reptiles, the majority of lipid deposition occurs via triglycerides packaged in very-low-density lipoproteins (VLDLs), based on physiological, histological, biochemical, comparative, and genomic evidence. I also discuss the evidence for non-avian reptiles using 'yolk-targeted' VLDLs during vitellogenesis. The major physiological states - feeding, fasting, and vitellogenesis - have different effects on plasma lipid metabolites, and I discuss the possibilities and potential problems of using plasma metabolites to diagnose feeding condition in non-avian reptiles.

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Section: Lipid Metabolism During Fastingmentioning

confidence: 99%

The physiology of lipid storage and use in reptiles

Price

2016

Biological Reviews

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“…Later on, in the 1960s, as obesity started to be a medical issue on a large scale, water fasting to treat morbid obesity and co-morbidities emerged under the names of zero calorie diet or total fasting [17]. The effects of this type of fasting, lasting weeks or months, particularly on obesity, have been extensively documented [18].…”

Section: Introductionmentioning

confidence: 99%

Unravelling the health effects of fasting: a long road from obesity treatment to healthy life span increase and improved cognition

et al. 2020

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In recent years a revival of interest has emerged in the health benefits of intermittent fasting and long-term fasting, as well as of other related nutritional strategies. In addition to meal size and composition a new focus on time and frequency of meals has gained attention. The present review will investigate the effects of the main forms of fasting, activating the metabolic switch from glucose to fat and ketones (G-to-K), starting 12-16 h after cessation or strong reduction of food intake. During fasting the deactivation of mTOR regulated nutrient signalling pathways and activation of the AMP protein kinase trigger cell repair and inhibit anabolic processes. Clinical and animal studies have clearly indicated that modulating diet and meal frequency, as well as application of fasting patterns, e.g. intermittent fasting, periodic fasting, or long-term fasting are part of a new lifestyle approach leading to increased life and health span, enhanced intrinsic defences against oxidative and metabolic stresses, improved cognition, as well as a decrease in cardiovascular risk in both obese and non-obese subjects. Finally, in order to better understand the mechanisms beyond fasting-related changes, human studies as well as non-human models closer to human physiology may offer useful clues. KEY-MESSAGES 1. Biochemical changes during fasting are characterised by a glucose to ketone switch, leading to a rise of ketones, advantageously used for brain energy, with consequent improved cognition. 2. Ketones reduce appetite and help maintain effective fasting. 3. Application of fasting patterns increases healthy life span and defences against oxidative and metabolic stresses. 4. Today's strategies for the use of therapeutic fasting are based on different protocols, generally relying on intermittent fasting, of different duration and calorie intake. 5. Long-term fasting, with durations between 5 and 21 days can be successfully repeated in the course of a year.

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“…Survival of prolonged fasts depends on an animal's ability to store and allocate energy from diverse macronutrient stores (Lignot and LeMaho, 2012;McCue, 2010McCue, , 2012. While many studies of amphibian metamorphosis have indirectly quantified lipid stress to fuel metabolism, no studies have directly quantified varied lipid and protein substrate use in amphibians.…”

Section: Introductionmentioning

confidence: 99%

Exogenous stress hormones alter energetic and nutrient costs of development and metamorphosis

Kirschman

McCue

Boyles

et al. 2017

Journal of Experimental Biology

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Variation in environmental conditions during larval life stages can shape development during critical windows and have lasting effects on the adult organism. Changes in larval developmental rates in response to environmental conditions, for example, can trade off with growth to determine body size and condition at metamorphosis, which can affect adult survival and fecundity. However, it is unclear how use of energy and nutrients shape trade-offs across life-stage transitions because no studies have quantified these costs of larval development and metamorphosis. We used an experimental approach to manipulate physiological stress in larval amphibians, along with respirometry and C-breath testing to quantify the energetic and nutritional costs of development and metamorphosis. Central to larval developmental responses to environmental conditions is the hypothalamic-pituitary-adrenal/interrenal (HPA/I) axis, which regulates development, as well as energy homeostasis and stress responses across many taxa. Given these pleiotropic effects of HPA/I activity, manipulation of the HPA/I axis may provide insight into costs of metamorphosis. We measured the energetic and nutritional costs across the entire larval period and metamorphosis in a larval amphibian exposed to exogenous glucocorticoid (GC) hormones - the primary hormone secreted by the HPA/I axis. We measured metabolic rates and dry mass across larval ontogeny, and quantified lipid stores and nutrient oxidation viaC-breath testing during metamorphosis, under control and GC-exposed conditions. Changes in dry mass match metamorphic states previously reported in the literature, but dynamics of metabolism were influenced by the transition from aquatic to terrestrial respiration. GC-treated larvae had lower dry mass, decreased fat stores and higher oxygen consumption during stages where controls were conserving energy. GC-treated larvae also oxidized greater amounts of C-labelled protein stores. These results provide evidence for a proximate cause of the physiological trade-off between larval growth and development, and provide insight into the energetic and nutrient costs that shape fitness trade-offs across life stages.

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A History of Modern Research into Fasting, Starvation, and Inanition

Cited by 15 publications

References 117 publications

The physiology of lipid storage and use in reptiles

The physiology of lipid storage and use in reptiles

Unravelling the health effects of fasting: a long road from obesity treatment to healthy life span increase and improved cognition

Exogenous stress hormones alter energetic and nutrient costs of development and metamorphosis

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