Effects Of Short-term Fasting Research Articles

Effect of short-term fasting on macronutrient self-selection in sea bass

The influence of two different fasting periods on macronutrient self-selection during refeeding was studied in sea bass. Twelve groups of three sea bass were kept under laboratory conditions with a 12:12 light–dark cycle and at 22.5°C. Each aquarium was provided with three self-feeders containing three different diets made up of two macronutrients: protein–fat, protein–carbohydrate, and carbohydrate–fat. The fish were allowed to acclimatise to the diets and laboratory conditions in 4 weeks, during which they selected a baseline diet of 51% protein, 16.5% carbohydrate, and 32.5% fat, in terms of digestible energy. The fish were then deprived of food for 6 days, after which they were permitted to refeed. When food demands stabilised, they were subjected to total food deprivation for another 2 weeks. The total energy demanded from all the macronutrients increased significantly during the first day after both fasting periods. The proportion of macronutrient self-selection after fasting periods remained unchanged in respect to the baseline, except for protein energy which remained high in the two first days of refeeding after the second fasting period (the 51% of total demanded energy from protein during the baseline period rising to 60%). In short, after two short fasting periods of different length, sea bass showed a compensatory ingestion of energy, with a slightly increased demand from protein after the longest fasting period.

Effect of fasting and refeeding on in vitro muscle cell proliferation in rainbow trout ( Oncorhynchus mykiss )

The effects of short-term fasting and refeeding were studied on satellite cells extracted from white epaxial muscle of juvenile rainbow trout (1-3 g body weight). In vitro changes in the proliferation of satellite cells were analyzed using bromodeoxyuridine (BrdU) incorporation over a 24-h period. Proliferation in fed control fish was characterized by an initial basal proliferation rate of 5-10% BrdU-labeled nuclei x day(-1), followed by an exponential increase at a rate of +18-20% x day(-1), up to a maximum of 60-70% BrdU-labeled nuclei x day(-1). Characteristics of satellite cells extracted from starved fish, namely extraction yield, morphology, and proliferation, were different from those of fed fish. Fasting (8-10 days) completely suppressed initial proliferation of satellite cells in vitro over a period of 4 days. After this delay, proliferation resumed and changes in proliferation rates over time were similar to those of the control group. In fish fed for 4 days after an 8-day fast, the initial proliferation rate and the changes in proliferation rates over time were completely restored. These findings demonstrate that satellite cells express different behavior depending on feeding status, which could be due to the presence of different satellite cell populations.

The effect of short-term fasting on shivering thermogenesis in Japanese quail chicks ( Coturnix coturnix japonica): indications for a significant role of diet-induced/growth related thermogenesis

(1) The effect of short-term fasting on metabolism and shivering thermogenesis was studied in 9-day-old Japanese quail. (2) After 31 h of fasting, heat production decreased 39% and body temperature over 2°C in the thermoneutral zone. The difference in heat production between control and fasting groups decreased with decreasing ambient temperature. (3) Despite the lower metabolic rate, the amplitudes of shivering EMGs were higher in fasted chicks, especially in pectoralis. This indicates that fasted quails used shivering to compensate the decrease in diet-induced/growth related thermogenesis. (4) In cold, conductance of control birds decreased simultaneously with increasing heat production while in fasted chicks, conductance decreased to its minimum before heat production was activated. (5) Japanese quail chicks adapt quickly to short-term fasting by decreasing metabolism but they maintain their ability to thermoregulate in cold. Diet-induced/growth related thermogenesis has a significant role in thermoregulation since it reduces the need of shivering thermogenesis.

The effect of acclimation to constant temperatures, pollution of food by heavy metals and short-term fasting on the metabolic activity of <i>Glomeris balcanica</i> (Diplopoda: Glomeridae)

Abstract. Changing temperature regime has an important effect on the respiratory metabolism of Glomeris balcanica. A left skewing response of animals to increasing temperature is revealed and modeled. Acclimation from fluctuating to constant temperatures depresses metabolism through a three-step process. Short-term acclimation results in strongly depressed metabolism, mid-term acclimation induces metabolic recovery, whereas long-term acclimation results in an irreversible decline of metabolic activity. Heavy metal burdens of food do not affect the left skewing thermal response of animals, although they depress metabolic levels at the high temperature range, shorten tolerance ranges by shifting down the upper tolerance threshold, enlarge optimal temperature range (metabolic constancy) and stimulate the faster activation of the metabolic compensatory mechanism. Finally, no effect of short-term fasting on respiration was detected.

Effect of short-term fasting on lipid kinetics in lean and obese women.

We evaluated whole body and regional adipose tissue lipid kinetics and norepinephrine (NE) spillover during brief fasting in six lean [body mass index (BMI) 21 +/- 1 kg/m2] and six upper-body obese (UBO; BMI 36 +/- 1 kg/m2) women. At 14 h of fasting, abdominal adipose tissue glycerol and free fatty acid (FFA) release rates were lower (P = 0.07), but whole body glycerol and FFA rates of appearance (Ra) were greater (P < 0.05) in obese than in lean subjects. At 22 h of fasting, glycerol and FFA Ra increased less in obese (19.8 +/- 7.0 and 87.1 +/- 30.3 micromol/min, respectively) than in lean (44.2 +/- 6.6 and 137.4 +/- 30.4 micromol/min, respectively; P < 0.05) women. The percent increase in glycerol Ra correlated closely with the percent decline in plasma insulin in both groups (r2 = 0.85; P < 0.05). Whole body NE spillover declined in lean (P < 0.05) but not obese subjects with continued fasting, whereas regional adipose tissue NE spillover did not change in either group. We conclude that, compared with lean women, in UBO women 1) basal adipose tissue lipolysis is lower, but whole body lipid kinetics is higher because of their greater fat mass; 2) the increase in lipolysis during fasting is blunted because of an attenuated decline in circulating insulin; and 3) downregulation of whole body sympathetic nervous system activity is impaired during fasting.

The effect of short-term fasting, phenobarbital and refeeding on apoptotic loss, cell replication and gene expression in rat liver during the promotion stage.

Previous work from this laboratory has reported on the effects of two sequential 5 day periods of fasting and subsequent refeeding on tumor promotion in multistage hepatocarcinogenesis in the rat (Carcinogenesis, 18, 159-166, 1997). In the present extension of the earlier study, the sequential fasting-refeeding regimen was begun at later time points (28 and 54 days post-initiation) than the first study. This was done to determine whether larger-sized altered hepatic foci (AHF) exhibited a depletion similar to that of the relatively small AHF in the published experiment and to study concomitant molecular changes during the fasting periods. Groups of animals were fasted in the presence and absence of 0.05% phenobarbital (PB) in the drinking water. During the fasting periods, both body and liver weights decreased dramatically, less in the fast begun at 54 days. This change was accompanied by a significant decrease in the bromodeoxyuridine (BrdU) labeling indices of hepatocytes within AHF. Apoptotic bodies increased dramatically in the non-focal (surrounding the AHF) hepatocytes during the fasting periods. These parameters were slightly lower in hepatocytes of rats administered PB during the fasting periods, most notably during the 54-66 day period. With the nick end-labeling method, the proportion of hepatocytes undergoing apoptosis was significantly higher in cells within AHF at the end of each of the fasting periods in all but one group. Concomitantly, the number of AHF and percentage of liver volume occupied by AHF decreased dramatically during the fasting periods. Refeeding caused a marked increase in BrdU labeling in hepatocytes within and surrounding AHF during the first week or two, most notably in animals not receiving PB during the fasting period. Both the number and volume percentage of liver AHF returned to control values within approximately 2 weeks of the refeeding regimen. Assays of nuclear DNA fragmentation with samples of whole liver indicated that a 'laddering' effect was most noticeable in livers of animals subjected to the fasting-refeeding regimen when phenobarbital was not present during the fasting period. Studies of the levels of mRNA of several genes in the total liver revealed that the expression of c-myc increased 3- to 9-fold during the fasting periods but rapidly returned to normal levels after refeeding. Levels of albumin and insulin-like growth factor I mRNAs decreased significantly during the fasting period, but rapidly reappeared on refeeding. These results indicate that the extensive loss of AHF during the short-term fasting periods occurs even when the number and volume of AHF are 10- to 50-fold greater at the beginning of the fast than the values published previously. Both the decrease in insulin growth factor I and the elevation of c-myc expression during the fasting period may indicate the role of these genes in the transcriptional regulation of hepatocyte apoptosis in both normal and preneoplastic hepatocytes in the rat.

The effect of short-term fasting, apolipoprotein E gene polymorphism, and sex on plasma lipids

The effect of 1 wk of supervised fasting on plasma lipid concentrations in subjects with different apolipoprotein E (apo E) phenotypes was studied in 58 healthy free-living volunteers. The participants consumed an 870-kJ(208 kcal)/d liquid diet containing fruit and berry juices, tea, and water. The decline in plasma total cholesterol during 1 wk of fasting was 0.46 mmol/L in women and 0.35 mmol/L in men. The decreases were significant in both women and men. The response patterns of plasma total cholesterol were not significantly different between the sexes. In men, the changes in plasma low-density-lipoprotein cholesterol during the fast differed significantly (P = 0.0181) between the apo E phenotypes, whereas in women there were no differences due to phenotype (P = 0.695). The magnitude of the change in plasma triacylglycerol during the fast was different between the sexes (P = 0.0099). The changes in plasma triacylglycerols differed significantly between apo E phenotype groups in men (P = 0.0295) but not in women (P = 0.0661). Statistical comparison between different apo E phenotypes was performed with and without the small apo E3,2+E2,2 group, with essentially similar results. During fasting, plasma high-density-lipoprotein cholesterol concentrations decreased slightly but not significantly. The study shows significant differences in the associations of apo E alleles and sex on plasma lipid responses during fasting and illustrates the importance of gene-diet interactions in the regulation of lipid metabolism in humans.

Effect of short-term fasting on free/dissociable insulin-like growth factor I concentrations in normal human serum

Effect of short-term fasting on free/dissociable insulin-like growth factor I concentrations in normal human serum

Effect of short-term fasting on free/dissociable insulin-like growth factor I concentrations in normal human serum.

A small portion of circulating insulin-like growth factor I (IGF-I) is detected in the free or readily dissociable state, which is thought to be the metabolically active form. The amount of free/dissociable IGF-I in serum is dependent on a complex interplay between the production rate and the concentrations of IGF-I and IGF-binding proteins (IGFBPs). IGF availability is also influenced by posttranslational changes in IGFBPs that affect the affinity of IGFBPs for IGF-I. In the present study, we examined whether a short term fast (approximately 12 h) alters the serum concentration of free/dissociable IGF-I, and whether these changes are associated with alterations in IGFBP-1 and the proteolysis status of IGFBP-3. Circulating free/dissociable IGF-I concentrations, as assessed by a two-site immunoradiometric assay, did not differ between fasting and 4 h after a morning meal (1.48 +/- 0.07 vs. 1.50 +/- 0.07 microgram/L, respectively). Likewise, free/dissociable IGF-I levels measured by RIA after separation by centrifugal ultrafiltration were not different between the two groups (1.43 +/- 0.14 vs. 1.38 +/- 0.18 microgram/L, respectively). IGF-I bioactivity, as measured by thymidine incorporation by fibroblasts, did not differ in fasting and 4-h postprandial sera. There was no difference in IGFBP-3 and total acid-ethanol-extractable IGF-I concentrations in serum from fasted and fed subjects. In contrast, the concentration of IGFBP-1 in the serum was increased approximately 5-fold in the fasted state compared to fed values. IGFBP-1 existed in a highly phosphorylated form under fasting conditions. There was no change in IGFBP-3 proteolysis assessed either in vivo or in vitro between the fasting and fed states. The results indicate that a physiologically relevant short term overnight fast does not alter the circulating levels of free/dissociable IGF-I despite a marked elevation in IGFBP-1.

SHORT TERM FASTING AFFECTS NEONATAL RAT BRAIN MONOAMINE LEVELS† 1290

Brain contents of monoamines increase continuously after birth. Effects of short term fasting in neonates are not fully examined. We applied the microdialysis method to 5-day-old rat pup(n=15) and studied changes of the brain extracellular levels of monoamines and their metabolites before and 5 hr fasting. A microdialysis probe was implanted into the left striatum and pups were fasted by separating their dams. Blood glucose (mean±SE: 6.5±0.6 vs 3.5±0.3mM*, before and after 5hr fasting, respectively) and serum tyrosine (256±30 vs 134±9mM*) decreased, but blood 3-hydroxybutyric acid (467±78 vs 1969±102μM*) serum tryptophan (51±2 vs 101±2mM*) increased significantly(p<0.01). The concentrations of norepinephrine, dopamine and dopa-acetate remained at the baseline levels for the first one to two hours and then decreased (p<0.001). Homovanillic acid unchanged throughout the experiment. 5-HIAA gradually increased (p<0.001). These results suggest that neonatal rat brain monoamines are easily affected by a short term fasting and their levels reflect the serum precursor amino acid levels, which is different from previous reports on adult rats. Our study exemplifies that this microdialysis method is applicable to neonatal rat brains to examine their monoamine levels change under various conditions without any other manipulations.Figure

Differential effects of short-term fasting on pulsatile thyrotropin, gonadotropin, and alpha-subunit secretion in healthy men--a clinical research center study

Differential effects of short-term fasting on pulsatile thyrotropin, gonadotropin, and alpha-subunit secretion in healthy men--a clinical research center study

Differential effects of short-term fasting on pulsatile thyrotropin, gonadotropin, and alpha-subunit secretion in healthy men--a clinical research center study.

In healthy subjects, short term fasting suppresses the hypothalamic-pituitary-thyroid and hypothalamic-pituitary-gonadal (HPG) axes, with decreased serum levels of TSH and LH. However, effects of fasting on pulsatile release of TSH, LH, FSH, and alpha-subunit are less clear. Eleven healthy young men each underwent two 2-day studies: a baseline study during normal caloric intake and a fasting study during 56 h of caloric deprivation. During the final 24 h of each study, blood samples were drawn every 15 min for measurement of serum TSH, LH, FSH, and alpha-subunit pulses. Fifty-six hours of fasting caused a 50% suppression of mean TSH levels and TSH pulse amplitude, without altering TSH pulse frequency. Nocturnal TSH pulse amplitude decreased by 60%, with abolition of the usual nocturnal TSH surge. Fasting suppressed mean LH levels and LH pulse amplitude by 30%, without affecting LH pulse frequency. In contrast, mean FSH levels only decreased by 13%, without changes in FSH pulse parameters, whereas mean alpha-subunit levels and pulse amplitude decreased by 20%. These data show that short term fasting has a greater suppressive effect on the hypothalamic-pituitary-thyroid axis than on the HPG axis. Within the HPG axis, FSH is more resistant to fasting-induced suppression than LH, implying discordant regulation of the two gonadotropins during nutritional deprivation. alpha-Subunit suppression during fasting appears to parallel that seen for LH.

Dynamic changes of growth hormone—binding protein concentrations in normal men and patients with acromegaly: Effects of short-term fasting

Plasma concentrations of growth hormone (GH) and GH-binding protein (GHBP) were measured at hourly intervals in five healthy men and five patients with acromegaly during the fed state and after a 5-day fast. GHBP concentrations (both total and complexed with endogenous GH) were analyzed by the ligand-mediated immunofunctional assay (LIFA). Total GHBP was similar in both groups during the fed state (104.4 ± 5.2 and 101.6 ± 10.3 pmol/L), did not exhibit a diurnal rhythm, and was unchanged by fasting (91.9 ± 5.4 and 109.9 ± 10.5 pmol/L, respectively). However, the GHBP GH complex concentration was significantly higher in acromegalics than in controls (41.0 ± 2.8 v 18.0 ± 2.2 pmol/L, respectively; P < .05), closely followed diurnal GH rhythm in normals, and was significantly correlated with mean 24-hour GH concentrations ( r = .86, P < .01). We conclude that plasma concentrations of GHBP are stable throughout the day and are unchanged either by short-term calorie deprivation or by chronic exposure to high levels of endogenous GH. In contrast, GHBP/GH complex concentrations are altered both acutely and chronically by ambient GH.

Acute fasting is ineffective in suppressing pituitary-gonadal function of pubertal male rats

Effects of short-term fasting (3-4 days) on pituitary-testicular functions were studied during sexual maturation in male rats at 25, 35, 45, 55, and 65 days of age. Among the main findings, testicular testosterone decreased by 41-68% at all ages (P < 0.01-0.05). The pituitary steady-state mRNA levels of the common alpha-subunit (28-55%) and follicle-stimulating hormone (FSH) beta-subunit (25-50%) decreased (P < 0.01-0.05) at 25, 55, and 65 days of age but not at 35 and 45 days; the luteinizing hormone (LH) beta-subunit did not respond at any age. Fasting decreased serum LH (P < 0.01) at 25, 55, and 65 days of age but not at 35 and 45 days. Likewise, fasting decreased pituitary and/or serum FSH only in the 25- and 65-day-old rats (P < 0.01-0.05). In conclusion, LH and FSH secretion, and the gene expression of common alpha- and FSH beta-subunits, decreased consistently during short-term fasting only in prepubertal (25 days) and adult (65 days) but not in peripubertal animals (35 and 45 days). Hence, the pubertal rise in gonadotropins represents such a strong positive induction that it largely overrides the antigonadotropic effect of fasting.

Effect of short-term fasting on plasma amino acids, glucose and insulin in non-pregnant and non-lactating Friesian cows

Effect of short-term fasting on plasma amino acids, glucose and insulin in non-pregnant and non-lactating Friesian cows

Effect of short-term fasting on plasma amino acids, glucose and insulin in non-pregnant and non-lactating Friesian cows

Effect of short-term fasting on plasma amino acids, glucose and insulin in non-pregnant and non-lactating Friesian cows

Effect of short-term fasting on nocturnal melatonin secretion in obesity

To investigate whether the function of pinealocytes is altered in obesity, nocturnal melatonin (MT) secretion was determined in nine healthy subjects and compared with that of eight obese individuals. Serum MT levels were measured every second hour between 6:00 pm and 8:00 am, and total nocturnal MT secretion (as reflected by the MT incremental area), MT peak time, and nocturnal urinary MT excretion were determined. None of these parameters differed significantly in the two groups. The obese subjects were reinvestigated after 2 days of complete fasting. This caused a decrease in body weight and basal blood glucose levels of 2.6 ± 0.2 kg (mean ± SEM, P < .001) and 1.5 ± 0.2 mmol/L ( P < .001), respectively, whereas serum cortisol levels remained unchanged. Short-term fasting reduced nocturnal MT secretion, as evidenced by MT incremental areas, which were reduced from 2.01 ± 0.26 before fasting to 1.64 ± 0.26 nmol/L · h after fasting ( P < .02). MT secretion peaks were reached simultaneously, and urinary MT excretion values did not change significantly in fasting. To see whether glucose supplementation during short-term fasting would normalize nocturnal MT secretion, we gave an additional seven obese subjects eight small oral doses of glucose (each dose, 0.5 g/kg body weight) at regular intervals during a 2-day fast. Their body weight decreased by 2.8 ± 0.4 kg ( P < .001), but blood glucose and cortisol concentrations were similar before and after the glucose-supplemented fast, as was the nocturnal MT secretion. These findings imply that pinealocytes of fed obese patients secrete normal amounts of MT during the night, but lose secretory potential during fasting-induced hypoglycemia. Since glucose supplementation during fasting returns MT secretion to normal, it is assumed that pinealocytes of obese individuals require a certain minimal glucose delivery to function normally.

The effect of short-term fasting and a single meal on protein synthesis and oxygen consumption in cod, Gadus morhua

Rates of protein synthesis and oxygen consumption (MO2) in cod were compared in both fasted and refed animals. During a 14-day fast both protein synthesis and respiration rates fell to stable values after 6 days. When a meal of whole sandeel at 6% body weight was fed to fish fasted for 6 days, protein synthesis and MO2 increased to a maximum at between 12 and 18 h after feeding. Peak MO2 was about twice the pre-feeding values, while whole animal protein synthesis increased four-fold. There were differences between tissues in the timing of maximum protein synthesis; the liver and stomach responded faster than the remainder of the body. Maximum protein synthesis rates in the liver and stomach occurred at 6 h after feeding, at which time their calculated contribution to total MO2 was 11%. Similar calculations suggested that the integrated increment in whole animal protein synthesis contributed between 23% and 44% of the post-prandial increase in MO2. It was concluded that protein synthesis is an important contributor to increased MO2 after feeding in cod.

Effect of short-term fasting on the lipolytic response to theophylline

We investigated the hypothesis that the increase in lipolysis that occurs in short-term (86-h) fasting is due to a decreased inhibitory influence of adenosine. In normal volunteers who fasted for 14 and 86 h, the response to adenosine receptor blockade was assessed by the infusion of theophylline at a rate sufficient to produce plasma concentrations (30 microM) that blocked adenosine receptors but that were well below the threshold for inhibition of phosphodiesterase. Lipolysis was assessed by determining the rate of appearance of glycerol using D-5-glycerol infusion. Fatty acid flux was also determined by means of [1-13C]palmitate infusion, and total fatty acid oxidation was determined by indirect calorimetry. There was a mild stimulatory effect of theophylline on lipolysis at 14 h. After the subjects fasted for 86 h, theophylline infusion caused a much greater increase in both lipolysis and fatty acid oxidation. These results suggest that the inhibitory effect of adenosine on lipolysis is increased during short-term fasting.

The effect of short-term fasting on processing of food cues in normal subjects

The effect of food deprivation on the selective processing of food- and body-size-related information was investigated using a modified version of the Stroop task. Fasting subjects were slower than controls in color-naming food-related words but not body-size-related words. This interference effect was found for both males and females. The findings could not be explained in terms of other variables and appeared to be a reflection of current concern with food and eating produced by the food deprivation.