Obese mice on a high-fat alternate-day fasting regimen lose weight and improve glucose tolerance

CCE and EODF as two distinct non-shivering thermogenesis models inducing weight loss

Increasing energy expenditure and reducing energy intake are considered two classical methods to induce weight loss. Weight loss through physical methods instead of drugs has been a popular research topic nowadays, but how these methods function in adipose and cause weight loss in body remains unclear. In this study, we set up chronic cold exposure (CCE) and every-other-day fasting (EODF) as two distinct models in long-term treatment to induce weight loss, recording their own characteristics in changes of body temperature and metabolism. We investigated the different types of non-shivering thermogenesis induced by CCE and EODF in white and brown adipose tissue through sympathetic nervous system (SNS), creatine-driven pathway, and fibroblast growth factor 21 (FGF21)-adiponectin axis. CCE and EODF could reduce body weight, lipid composition, increase insulin sensitivity, promote the browning of white fat, and increase the expression of endogenous FGF21 in adipose tissue. CCE stimulated the SNS and increased the thermogenic function of brown fat, and EODF increased the activity of protein kinase in white fat. In this study, we further explained the thermogenic mechanism function in adipose and metabolic benefits of the stable phenotype through physical treatments used for weight loss, providing more details for the literature on weight loss models. The influence on metabolism, non-shivering thermogenesis, endogenous FGF21, and ADPN changes in the long-term treatment of distinct methods (increasing energy expenditure and decreasing energy intake) to induce weight loss.

The administration of Exendin-4 and CCK affects food intake differentially in female and male rats tested on an alternate day fasting paradigm

Alternate day fasting (ADF) which involves the repetition of a 2-day cycle of a day of free access to food followed by a day of limited or no access to food, is an effective dietary intervention for weight loss in both humans and rats. We have previously reported that when presented with a high energy (HE) and standard chow diet, rats maintained on an ADF schedule displayed decreased HE diet preference compared to controls. Both male and female ADF rats increased overall intake of chow. However, this increase was driven by both meal size and meal number for males and only number of meals for females. Administration of cholecystokinin (CCK) or the glucagon-like peptide 1 (GLP-1) receptor agonist Exendin-4 (Ex-4) reduces food intake. It appears that CCK decreases food intake primarily through satiety signals whereas GLP-1 signaling may reduce intake by satiety and reward cues. Here, female and male rats were administered (i.p.) saline, 3.0 µg/kg Ex-4 (3 h before test), 3.0 µg/kg CCK (15 min before test) or a combination of both. Next, all rats were presented 23-h access to both HE diet and chow following food-restriction (ADF) or free access to chow (CON). Compared to saline-control sessions, administration of the combination of Ex-4 and CCK, but not Ex-4 or CCK alone, resulted in a decrease in both HE and chow intake early in the session for male ADF rats but the combination primarily decreased chow diet intake early in the session for female ADF rats. Thus, it appears that under these energy homeostatic conditions, administration of Ex-4 or CCK alone does not affect intake in ADF rats, but the combination produces decreases in feeding that are more than the sum of their individual effects. These findings support a role for the combination of GLP-1 and CCK signaling in the changes in diet preference induced by an alternate day fasting paradigm differentially in female and male rats.

Dietary patterns and cardiometabolic health: Clinical evidence and mechanism

For centuries, the search for nutritional interventions to underpin cardiovascular treatment and prevention guidelines has contributed to the rapid development of the field of dietary patterns and cardiometabolic disease (CMD). Numerous studies have demonstrated that healthy dietary patterns with emphasis on food-based recommendations are the gold standard for extending lifespan and reducing the risks of CMD and mortality. Healthy dietary patterns include various permutations of energy restriction, macronutrients, and food intake patterns such as calorie restriction, intermittent fasting, Mediterranean diet, plant-based diets, etc. Early implementation of healthy dietary patterns in patients with CMD is encouraged, but an understanding of the mechanisms by which these patterns trigger cardiometabolic benefits remains incomplete. Hence, this review examined several dietary patterns that may improve cardiometabolic health, including restrictive dietary patterns, regional dietary patterns, and diets based on controlled macronutrients and food groups, summarizing cutting-edge evidence and potential mechanisms for CMD prevention and treatment. Particularly, considering individual differences in responses to dietary composition and nutritional changes in organ tissue diversity, we highlighted the critical role of individual gut microbiota in the crosstalk between diet and CMD and recommend a more precise and dynamic nutritional strategy for CMD by developing dietary patterns based on individual gut microbiota profiles.

Maternal intermittent fasting in mice disrupts the intestinal barrier leading to metabolic disorder in adult offspring

Maternal nutrition plays a critical role in energy metabolism of offspring. We aim to elucidate the effect of long-term intermittent fasting (IF) before pregnancy on health outcomes of offspring. Here we show long-term IF before pregnancy disrupts intestinal homeostasis of offspring with subsequent disorder of glucose and lipid metabolism. This occurs through the reduction in beneficial microbiota such as Lactobacillus_intestinalis. Our observations further support the concept that intestinal microbiota in offspring is vulnerable to maternal nutrition, and its homeostasis is critical for the integrity of intestinal barrier and metabolic homeostasis.

The Health-Promoting Effects and the Mechanism of Intermittent Fasting

Intermittent fasting (IF) is an eating pattern in which individuals go extended periods with little or no energy intake after consuming regular food in intervening periods. IF has several health-promoting effects. It can effectively reduce weight, fasting insulin levels, and blood glucose levels. It can also increase the antitumor activity of medicines and cause improvement in the case of neurological diseases, such as memory deficit, to achieve enhanced metabolic function and prolonged longevity. Additionally, IF activates several biological pathways to induce autophagy, encourages cell renewal, prevents cancer cells from multiplying and spreading, and delays senescence. However, IF has specific adverse effects and limitations when it comes to people of a particular age and gender. Hence, a more systematic study on the health-promoting effects and safety of IF is needed. This article reviewed the research on the health-promoting effects of IF, providing a theoretical basis, direction for subsequent basic research, and information related to the clinical application of IF.

A long-term obesogenic high-fat diet in mice partially dampens the anti-frailty benefits of late-life intermittent fasting

The global obesity pandemic coupled with ever-growing life expectancies equates to hundreds of millions of individuals with potentially longer but not healthier lives. Aging is one of the risk factors for numerous maladies such as metabolic disorder and frailty, which are exacerbated under obesity. Thus, therapeutic approaches that address obesity to ultimately improve affected individuals' quality of life and extend their lifespan are needed. We previously reported that the every other day (EOD) fasting initiated late-life improved metabolic, musculoskeletal, and cognitive endpoints in standard rodent diet-fed mice. In the present study, using the same dietary intervention methodology, we tested if 2.5 months of EOD fasting could improve metabolic, physiological, and cognitive endpoints in mice after an 18 month obesogenic high-fat diet (HFD). The positive effects of EOD fasting were generally consistent across the endpoints; EOD fasting decreased total body mass, maintained more %lean mass, improved glucose tolerance and utilization, and improved neuromuscular function. In contrast to our previous study, grip strength, hippocampal-dependent memory, and renal hydrogen sulfide (H₂S) production were not improved by the HFD EOD fasting. Thus, efficacy for late-life initiated intermittent fasting to improve specific frailty markers may be partially dependent on nutritional compositions of the diet.

Alternate-day fasting, a high-sucrose/caloric diet and praziquantel treatment influence biochemical and behavioral parameters during Schistosoma mansoni infection in male BALB/c mice

Schistosoma mansoni-induced granulomas result in severe damage to the host's liver, as well as neurological and metabolic disorders. We evaluated the biochemical and behavioral changes during schistosomiasis under three diet protocols: ad libitum (AL), alternate-day fasting (ADF) and a high-sucrose/caloric diet (HSD). Healthy male BALB/c mice were divided into noninfected, matched infected and infected/treated [praziquantel (PZQ)] groups. Caloric intake and energy efficiency coefficients associated with diets were measured. Behavioral (exploratory and locomotor) and biochemical (glucose, triglycerides, total cholesterol, AST, ALT, ALP, and γ-GT) tests and histological analysis were performed. Fifteen weeks postinfection, HSD and PZQ promoted weight gain, with higher caloric consumption than ADF (p < 0.05), reflecting serum glucose levels and lipid profiles. HSD and PZQ prevented liver dysfunction (AST and ALT) and significantly prevented increases in granuloma area (p < 0.05). HSD and PZQ also significantly improved mouse physical performance in exploratory and locomotor behavior (p < 0.05), reversing the impaired motivation caused by infection. These findings showed that ADF worsened the course of S. mansoni infection, while HSD and PZQ, even with synergistic effects, prevented and/or attenuated biochemical and behavioral impairment from infection.

Hepatic Suppression of Mitochondrial Complex II Assembly Drives Systemic Metabolic Benefits

Alternate day fasting (ADF), the most popular form of caloric restriction, has shown to improve metabolic health in preclinical subjects, while intrinsic network underpinning the process remains unclear. Here, it is found that liver undergoes dramatic metabolic reprogramming during ADF, accompanied surprisingly with unique complex II dysfunction attributing to suspended complex II assembly via suppressing SDHAF4, a recently identified assembly factor. Despite moderate mitochondrial complex II dysfunction, hepatic Sdhaf4 knockout mice present intriguingly improved glucose tolerance and systemic insulin sensitivity, consistent with mice after ADF intervention. Mechanistically, it is found that hepatocytes activate arginine-nitric oxide (NO) biosynthesis axle in response to complex II and citric acid cycle dysfunction, the release of NO from liver can target muscle and adipocytes in addition to its autocrine action for enhanced insulin sensitivity. These results highlight the pivotal role of liver in ADF-associated systemic benefits, and suggest that targeting hepatic complex II assembly can be an intriguing strategy against metabolic disorders.

Alternate-Day High Fat-Normal Chow Diet Ameliorates HFD-Induced Obesity and Restores Intestinal Immunity

PURPOSE

To investigate the effect of alternating-day diet regimens on high-fat diet-induced metabolic disorders in mice.

MATERIALS AND METHODS

Eight-week-old C57BL/6J mice were fed with either a continuous normal chow diet (CD, n = 10), a continuous high-fat diet (HFD, n = 10), HFD alternating every 24 h with fasting (H-ADF, n = 20), or HFD alternating every 24 h with chow diet (H-ADC, n = 20) for 12 weeks. Weights were recorded weekly and oral glucose tolerance tests were performed 6 weeks after initiating the regimens. At the end of the study, blood samples were collected and serum insulin and lipids were measured; tissues were collected for histology and RNA-seq analysis.

RESULTS

HFD significantly increased body weight and fat percentage, while HFD alternating with fasting or CD did not significantly affect body weight and fat percentage. The glucose intolerance induced by HFD was also significantly ameliorated in these two diet intervention groups. HFD-induced elevation of total cholesterol, low-density lipoprotein and insulin were also reduced in H-ADF and H-ADC groups. Moreover, HFD-disturbed immunity, presented by Lysozyme C-1 (Lyz1) immunostaining and RNA-seq, was restored in both alternating-regimen groups, especially, with H-ADC. At the transcriptional level, some cell proliferation and lipid absorption pathways were down-regulated in both H-ADF and H-ADC groups compared to the continuous HFD group.

CONCLUSION

Alternating an HFD with a normal diet every 24 h effectively controls weight and prevents metabolic disorders and may act by affecting both fat absorption and intestinal immunity.

Intermittent fasting: from calories to time restriction

The global human population has recently experienced an increase in life expectancy with a mounting concern about the steady rise in the incidence of age-associated chronic diseases and socio-economic burden. Calorie restriction (CR), the reduction of energy intake without malnutrition, is a dietary manipulation that can increase health and longevity in most model organisms. However, the practice of CR in day-to-day life is a challenging long-term goal for human intervention. Recently, daily fasting length and periodicity have emerged as potential drivers behind CR's beneficial health effects. Numerous strategies and eating patterns have been successfully developed to recapitulate many of CR's benefits without its austerity. These novel feeding protocols range from shortened meal timing designed to interact with our circadian system (e.g., daily time-restricted feeding) to more extended fasting regimens known as intermittent fasting. Here, we provide a glimpse of the current status of knowledge on different strategies to reap the benefits of CR on metabolic health in murine models and in humans, without the rigor of continuous reduction in caloric intake as presented at the USU State of the Science Symposium.

Intermittent fasting ameliorates di-(2-ethylhexyl) phthalate-induced precocious puberty in female rats: A study of the hypothalamic-pituitary-gonadal axis

Di-(2-ethylhexyl) phthalate has been reported to interfere with the development and function of animal reproductive systems. However, hardly any studies provide methods to minimize or prevent the adverse effects of DEHP on reproduction. The energy balance state of mammals is closely related to reproductive activities, and the reproductive axis can regulate reproductive activities according to changes in the body's energy balance state. In this study, the effects of every other day fasting (EODF), as a way of intermittent fasting, on preventing the precocious puberty induced by DEHP in female rats was studied. EODF significantly improved the advancement of vaginal opening age (as the markers of puberty onset) and elevated serum levels of luteinizing hormone and estradiol (detected by ELISA) induced by 5 mg kg^-1 DEHP exposure (D5). The mRNA and western blot results showed that the EODF could minimized the increase of gonadotropin-releasing hormone expression induced by DEHP exposure. The administration of DEHP could elevate the levels of kisspeptin protein and the number of kisspeptin-immunoreactive neurons in anteroventral periventricular nucleu, and this increase was diminished considerably by EODF treatment. In contrast, the D5 and D0 groups showed no remarkable difference in the level of Kiss1 expression in arcuate nucleus, whereas the D5 + EODF group had a remarkable decrease in kisspeptin expression as compared with the other two groups. Our results indicated that EODF might inhibit the acceleration of puberty onset induced by DEHP exposure via HPG axis.

Fasting: How to Guide

Fasting potentials are the most interesting topics in the Nutritional Era. Fasting consists of the catabolism of lipids, proteins, and carbohydrates to maintain blood glucose levels in a normal range. The action mechanisms of fasting were firstly understood in minor organisms and later in humans. Nutritional interventions of caloric restriction could attenuate age-associated epigenetic alterations and could have a protective effect against cellular alterations, promoting longevity and health span. While most fasting studies point out the weight and fat mass decreases, it is important to define specific guidelines for fasting and non-fasting days to enhance adherence, minimize the dropout rates of the interventions, and maximize body composition improvement. Although the panorama of evidence on fasting and caloric restriction is wide, there is a lack of a safe fasting protocol to guide physicians in its prescription. The main goal is to identify a how to use guide, a major posology of fasting, inserted within a huge dietetic personalized strategy leading to an optimal and healthy nutritional status.

Health Effects of Alternate Day Fasting Versus Pair-Fed Caloric Restriction in Diet-Induced Obese C57Bl/6J Male Mice

Alternate day fasting (ADF) induces weight loss and improves various markers of health in rodents and humans. However, it is unclear whether the benefits of ADF are derived from the lower caloric intake of ADF or from the 24-h fasting period. Therefore, this study directly compared selected markers for health – such as glucose control, body weight, liver triglycerides, T cell frequencies, and others – in high-fat (60% calories from fat) diet-induced obese mice subjected to either ADF or caloric restriction (CR). Obese mice were randomly assigned to one of four groups: (1) ADF: remained on the high-fat diet, but fed on alternate days (n = 5), (2) PF: remained on the high-fat diet, but pair-fed to the ADF group (n = 5), (3) LF: moved to a chow ad libitum diet (n = 5; 17% calories from fat), and (4) HF: remained on the high-fat ad libitum diet (n = 5). An additional group of non-obese mice maintained on a chow diet since weaning were used as controls (CON: n = 5). After 10 weeks, ADF, PF, and LF mice ate fewer kcals, had a lower body mass, had smaller epididymal fat pads, improved glucose tolerance, and had a lower hepatic triglyceride content relative to HF mice (p < 0.05), but none reached that of CON mice in these measures. T cell frequencies of the spleen, blood, and mesenteric lymph nodes were reduced in ADF, PF, and HF compared to the CON group. Importantly, there were no significant differences between the ADF and PF groups in any of the measurements made in the current study. These data suggest that ADF, PF, and LF diets each lead to improved markers of health relative to high-fat diet-induced obese mice, and that the caloric restriction associated with ADF is the major factor for the noted improvements.

Intermittent Fasting Improves Lipid Metabolism Through Changes in Gut Microbiota in Diet-Induced Obese Mice

Background

The mechanism of how intermittent fasting (IF) improves metabolism is not fully understood. Our study aimed to explore the effect of IF on lipid metabolism in obese mice, specifically on the intestinal flora.

Material/Methods

Diet-induced obese (DIO) mice were subjected to ad libitum (AL) feeding or IF (alternate-day fasting) for 30 days. We examined the lipid metabolism, fat distribution, gene expression of lipid metabolism, and intestinal flora in the mice.

Results

Despite having access to the same high-fat diet as the AL-fed groups, IF mice displayed pronounced weight loss, and their lipid metabolism significantly improved, mainly reflected in lower serum lipid levels and ameliorated liver steatosis. IF also reduced metabolic endotoxemia in DIO mice. The 16S ribosomal deoxyribonucleic acid gene amplicon sequencing suggested that IF did not change the community richness but had a tendency to increase community diversity in the intestinal flora. In addition, IF significantly reduced the ratio of Firmicutes to Bacteroidetes and increased the relative abundance of Allobaculum in the intestinal flora.

Conclusions

IF can improve fat metabolism, reduce fat accumulation, promote white fat conversion to beige, and improve gut microbiota.

Intermittent Fasting for Twelve Weeks Leads to Increases in Fat Mass and Hyperinsulinemia in Young Female Wistar Rats

Fasting is known to cause physiological changes in the endocrine pancreas, including decreased insulin secretion and increased reactive oxygen species (ROS) production. However, there is no consensus about the long-term effects of intermittent fasting (IF), which can involve up to 24 hours of fasting interspersed with normal feeding days. In the present study, we analyzed the effects of alternate-day IF for 12 weeks in a developing and healthy organism. Female 30-day-old Wistar rats were randomly divided into two groups: control, with free access to standard rodent chow; and IF, subjected to 24-hour fasts intercalated with 24-hours of free access to the same chow. Alternate-day IF decreased weight gain and food intake. Surprisingly, IF also elevated plasma insulin concentrations, both at baseline and after glucose administration collected during oGTT. After 12 weeks of dietary intervention, pancreatic islets displayed increased ROS production and apoptosis. Despite their lower body weight, IF animals had increased fat reserves and decreased muscle mass. Taken together, these findings suggest that alternate-day IF promote β -cell dysfunction, especially in developing animals. More long-term research is necessary to define the best IF protocol to reduce side effects.

Intermittent fasting benefits on alpha- and beta-cell arrangement in diet-induced obese mice pancreatic islet

AIMS

There is a pancreatic islet adaptation in obese subjects, resulting in insulin resistance and diabetes type 2. We studied the effect of intermittent fasting (IntF) on the islet structure of diet-induced obese (DIO) mice.

METHODS

Three-month-old male mice fed a control diet (C, 10% Kcal fat) or a high-fat diet (HF, 50% Kcal fat) for two months (n = 20 each group). Then, half of each group did IntF (alternating 24 h fed/24 h fast), continuing in their diets four more weeks: C, C-IntF, HF, HF-IntF. Islets were prepared to microscopy or isolated for molecular analysis.

RESULTS

HF group (vs. C group) showed hyperglycemia, hyperinsulinemia, hyperleptinemia, hypoadiponectinemia, glucose intolerance, insulin resistance, and islet hypertrophy with a consequent higher both the alpha-cell and beta-cell masses. In the HF group (vs. C), there was low PDX1 (pancreatic and duodenal homeobox 1), and IntF did not alter PDX1. There was a low p-AKT/AKT ratio (protein kinase B), and IntF enhanced it. Also, tumor suppressor p53 was increased, and IntF decreased it. IL (interleukin) -6 was higher in the HF group (vs. C), and HF-IntF (vs. C-IntF). Any significant change in NFkB was seen among groups.

CONCLUSIONS

IntF improves pancreatic islet structure in DIO mice, even with continued HF diet intake, primarily considering on the alpha- and beta-cell masses regulation, then improving insulin signaling and decreasing cell apoptosis. Future research should explore whether the shortening of the IntF extend could maintain the benefits observed in the long term.

Time of Feeding Alters Obesity-Associated Parameters and Gut Bacterial Communities, but Not Fungal Populations, in C57BL/6 Male Mice

BACKGROUND

Fasting and timed feeding strategies normalize obesity parameters even under high-fat dietary intake. Although previous work demonstrated that these dietary strategies reduce adiposity and improve metabolic health, limited work has examined intestinal microbial communities.

OBJECTIVES

We determined whether timed feeding modifies the composition of the intestinal microbiome and mycobiome (yeast and fungi).

METHODS

Male C57BL/6 mice were fed a high-fat diet (HF) for 6 wk. Animals were then randomly assigned to the following groups (n = 8-10/group): 1) HF ad libitum; 2) purified high-fiber diet (Daniel Fast, DF); 3) HF-time-restricted feeding (TRF) (6 h); 4) HF-alternate-day fasting (ADF); or 5) HF at 80% total caloric restriction (CR). After 8 wk, obesity and gut parameters were characterized. We also examined changes to the gut microbiome and mycobiome before, during, and following dietary interventions.

RESULTS

Body mass gain was reduced with all restricted dietary groups. HF-fed microbiota displayed lower α-diversity along with reduced phylum levels of Bacteroidetes and increased Firmicutes. Animals switched from HF to DF demonstrated a rapid transition in bacterial taxonomic composition, α-, and β-diversity that initially resembled HF, but was distinct after 4 and 8 wk of DF feeding. Time-or calorie-restricted HF-fed groups did not show changes at the phylum level, but α-diversity was increased, with specific genera altered. Six weeks of HF feeding reduced various fungal populations, particularly Alternaria, Aspergillus, Cladosporium, and Talaromyces, and increased Candida, Hanseniaspora, and Kurtzmaniella. However, 8 wk of intervention did not change the fungal populations, with the most abundant genera being Candida, Penicillium, and Hanseniaspora.

CONCLUSIONS

These data suggest that timed-feeding protocols and diet composition do not significantly affect the gut fungal community, despite inducing measurable shifts in the bacterial population that coincide with improvements in metabolism.

Time-restricted feeding improves markers of cardiometabolic health in physically active college-age men: a 4-week randomized pre-post pilot study

Time-restricted feeding (TRF) has been shown to improve body composition, blood lipids, and reduce markers of inflammation and oxidative stress. However, most of these studies come from rodent models and small human samples, and it is not clear if the benefits are dependent upon a caloric deficit, or the time restriction nature of TRF. Based off of previous research, we hypothesized that humans following an ad libitum TRF protocol would reduce caloric intake and this caloric deficit would be associated with greater improvements in cardiometabolic health including blood pressure, body composition, blood lipids, and markers of inflammation and antioxidant status compared to an isocaloric TRF protocol. The purpose of this study was to: (1) examine the impact of TRF on markers of cardio-metabolic health and antioxidant status and (2) determine if the adaptations from TRF would differ under ad libitum compared to isocaloric conditions. Twenty-three healthy men were randomized to either an ad libitum or isocaloric 16:8 (fasting: feeding) TRF protocol. A total of 22 men completed the 28-day TRF protocol (mean ± SD; age: 22 ± 2.5 yrs.; height: 178.4 ± 6.9 cm; weight: 90.3 ± 24 kg; BMI: 28.5 ± 8.3 kg/m²). Fasting blood samples were analyzed for glucose, lipids, as well as adiponectin, human growth hormone, insulin, cortisol, C-reactive protein, superoxide dismutase, total nitrate/nitrite, and glutathione. Time-restricted feeding in both groups was associated with significant (P < .05) reductions in body fat, blood pressure, and significant increases in adiponectin and HDL-c. No changes in caloric intake were detected. In summary, the results from this pilot study in metabolically healthy, active young men, suggest that TRF can improve markers of cardiometabolic health.

Alternate Day Fasting Improves Physiological and Molecular Markers of Aging in Healthy, Non-obese Humans

Caloric restriction and intermittent fasting are known to prolong life- and healthspan in model organisms, while their effects on humans are less well studied. In a randomized controlled trial study (ClinicalTrials.gov identifier: NCT02673515), we show that 4 weeks of strict alternate day fasting (ADF) improved markers of general health in healthy, middle-aged humans while causing a 37% calorie reduction on average. No adverse effects occurred even after >6 months. ADF improved cardiovascular markers, reduced fat mass (particularly the trunk fat), improving the fat-to-lean ratio, and increased β-hydroxybutyrate, even on non-fasting days. On fasting days, the pro-aging amino-acid methionine, among others, was periodically depleted, while polyunsaturated fatty acids were elevated. We found reduced levels sICAM-1 (an age-associated inflammatory marker), low-density lipoprotein, and the metabolic regulator triiodothyronine after long-term ADF. These results shed light on the physiological impact of ADF and supports its safety. ADF could eventually become a clinically relevant intervention.

Alternate-day feeding leads to improved glucose regulation on fasting days without significant weight loss in genetically obese mice

Alternate-day fasting (ADF) is effective for weight loss and increases insulin sensitivity in diet-induced obese rodents. However, the efficacy of ADF in genetic models of obesity has not been comprehensively studied. Mice that are deficient in leptin ( ob/ob mice) are obese, diabetic, and prone to deep bouts of torpor when fasted. We tested the hypotheses that an ADF protocol in ob/ob mice would result in 1) induction of torpor on fasted days, 2) minimal body weight loss if the mice experienced torpor, and 3) no improvement in glucose control in the absence of weight loss. Female ob/ob mice and littermate controls were assigned to 1) an ad libitum regimen or 2) an ADF regimen, consisting of fasting every other day with ad libitum feeding between fasts. Over a 19-day period, littermate control mice on the ADF regimen consumed the same amount of food as littermate control mice on the ad libitum regimen, whereas the ADF ob/ob mice consumed 37% less food than ad libitum ob/ob mice. Fasting days, but not fed days, led to torpor in both genotypes. Fasting days, but not fed days, led to weight loss in both genotypes relative to ad libitum controls. Fasting days, but not fed days, produced enhanced insulin sensitivity in both genotypes and normalized circulating glucose in ob/ob mice. These data demonstrate improved glucose control on fasting days with the use of ADF in a genetic model of obesity in the face of minimal weight loss.

Effects of methionine partially replaced by methionyl-methionine dipeptide on intestinal function in methionine-deficient pregnant mice

This study was to compare the effects of parenteral supplementation of methionyl-methionine (Met-Met) or Met on intestinal barrier function in Met-deficient pregnant mice. Pregnant mice were randomly divided into three groups. The Control group was provided a diet containing Met and received i.p. injection of saline. The Met group was fed the same diet but without Met and received daily i.p. injection of 35% of the Met contained in the control diet. The Met-Met group was treated the same as the Met group, except that 25% of the Met injected was replaced with Met-Met. Met-Met promoted villus surface area in ileum compared with Met alone. In addition, the mRNA abundance of amino acid and glucose transporters in the small intestine was altered with Met-Met. Moreover, Met-Met increased tight junction protein and decreased apoptosis-related proteins expression in the jejunum and ileum. These results suggest that Met-Met can promote intestinal function over Met alone in Met-deficient mice.

Beneficial effects of intermittent fasting on steatosis and inflammation of the liver in mice fed a high-fat or a high-fructose diet

OBJECTIVE

Intermittent fasting (IF) is a nutritional intervention with significant metabolic effects on the liver that are not yet fully understood. The aim of this study was to investigate the effects of IF on body mass, lipid profile, glucose metabolism, liver lipogenesis, β-oxidation, and inflammation.

METHODS

We used cellular and molecular techniques to investigate the effects of IF on 3-mo-old male C57 BL/6 mice that were fed control (10% kcal fat), high-fat (HF; 50% kcal fat), or high-fructose (HFr; 50% kcal fructose) diets for 8 wk. Half of the animals were submitted to IF (1 d fed, 1 d fast) for an additional 4 wk.

RESULTS

Although food intake on the fed day did not differ between the groups, mice in the HF and HFr groups showed diminished body mass, total cholesterol, and triacylglycerol levels. Also, plasma adiponectin increased in the HFr group and leptin decreased in the HF mice. Oral glucose tolerance test and insulin were ameliorated by IF, regardless of the diet consumed (HF or HFr), and decreased hepatic lipogenesis and increased β-oxidation markers, resulting in a reduction of the hepatic steatosis and inflammation.

CONCLUSIONS

There were beneficial effects of IF even with the continuity of the obesogenic diet and proinflammatory diet in mice. It is recommended that based on the beneficial effects of IF on glucose and liver metabolism and inflammation that IF be a coadjutant factor in the treatment of hepatic metabolic issues and steatosis.

A Comparison of Dietary and Caloric Restriction Models on Body Composition, Physical Performance, and Metabolic Health in Young Mice

Time-restricted feeding (TRF), alternate day fasting (ADF), and the dietary restriction model known as the Daniel Fast (DF; a vegan/non-processed food diet plan) have garnered attention recently as nutritional interventions to combat obesity. We compared the effects of various dietary models on body composition, physical performance, and metabolic health in C57BL/6 mice. Sixty young C57BL/6 male mice were assigned a diet of TRF, ADF, DF, caloric restriction (CR), a high-fat Western diet (HF) fed ad libitum, or standard rodent chow for eight weeks. Their body composition, run time to exhaustion, fasting glucose, insulin, and glucose tolerance test area under the glucose curve (AUC) were determined. Compared to the HF group, all groups displayed significantly less weight and fat mass gain, as well as non-significant changes in fat-free mass. Additionally, although not statistically significant, all groups displayed greater run time to exhaustion relative to the HF group. Compared to the HF group, all groups demonstrated significantly lower fasting glucose, insulin, and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), as well as improved glucose tolerance, and the ADF group displayed the best fasting glucose and glucose tolerance results, with DF having the best HOMA-IR. All investigated fasting protocols may improve body composition, measures of insulin sensitivity, and physical performance compared to a high-fat Western diet. The DF and ADF protocols are most favorable with regards to insulin sensitivity and glucose tolerance. Since our selected dietary protocols have also been investigated in humans with success, it is plausible to consider that these dietary models could prove beneficial to men and women seeking improved body composition and metabolic health.

Intermittent Fasting Improves Glucose Tolerance and Promotes Adipose Tissue Remodeling in Male Mice Fed a High-Fat Diet

Obesity is associated with increased macrophage and extracellular matrix accumulation in adipose tissue, which can be partially reversed following weight loss by daily caloric restriction. This study examined the effects of 8 weeks of intermittent fasting (IF; 24-hour fast on 3 nonconsecutive days per week) in mice fed a chow or high-fat diet (HFD; 43% fat) on markers of adipose tissue inflammation and fibrosis. We found that IF decreased energy intake, body weight, and fat cell size in HFD-fed mice and decreased fat mass and improved glucose tolerance in chow- and HFD-fed mice. IF decreased mRNA levels of macrophage markers (Lgals3, Itgax, Ccl2, and Ccl3) in inguinal and gonadal fat, as well as adipose tissue macrophage numbers in HFD-fed mice only, and altered genes involved in NLRP3 inflammasome pathway in both diet groups. IF increased mRNA levels of matrix metallopeptidase 9, which is involved in extracellular matrix degradation, and reduced mRNA levels of collagen 6 α-1 and tissue inhibitor of matrix metallopeptidase 1, as well as fibrosis in gonadal fat in HFD-fed mice. In summary, our results show that intermittent fasting improved glucose tolerance in chow- and HFD-fed mice and ameliorated adipose tissue inflammation and fibrosis in HFD-fed mice.

Alternate day fasting decreases preference for a calorically dense diet by increasing chow intake and altering meal pattern parameters

Alternate day fasting (ADF) is an effective dietary strategy for weight loss in both humans and rats. However, fasting can elicit hyperphagia in rats, particularly upon access to a calorically dense, high-energy (HE) diet. To examine the effects of ADF on HE diet preference, male and female Sprague-Dawley rats were randomly assigned to receive either ad-libitum or alternate day access to both chow and HE food. Meal pattern analysis was conducted to provide a more detailed explanation of changes in HE preference. ADF rats had a decreased preference for the HE diet compared to controls. Both male and female ADF rats increased in overall intake of chow. However, for male ADF rats, the decrease in HE preference was driven by an increase in both size and number of chow meals; for females, it was driven only by an increase in number of chow meals. Meal size is controlled by both positive feedback (e.g., from the oral cavity) and negative feedback (e.g., from postoral inhibitory signals). Thus, for males, fasting appeared to increase orosensory stimulation and/or decrease sensitivity to inhibitory cues towards chow. For females, fasting appeared to decrease sensitivity to inhibitory cues towards chow. The decrease in HE preference observed in the current study may contribute to the effectiveness of ADF as a dietary strategy for weight loss.

Emerging Anti-Aging Strategies - Scientific Basis and Efficacy

The prevalence of age-related diseases is in an upward trend due to increased life expectancy in humans. Age-related conditions are among the leading causes of morbidity and death worldwide currently. Therefore, there is an urgent need to find apt interventions that slow down aging and reduce or postpone the incidence of debilitating age-related diseases. This review discusses the efficacy of emerging anti-aging approaches for maintaining better health in old age. There are many anti-aging strategies in development, which include procedures such as augmentation of autophagy, elimination of senescent cells, transfusion of plasma from young blood, intermittent fasting, enhancement of adult neurogenesis, physical exercise, antioxidant intake, and stem cell therapy. Multiple pre-clinical studies suggest that administration of autophagy enhancers, senolytic drugs, plasma from young blood, drugs that enhance neurogenesis and BDNF are promising approaches to sustain normal health during aging and also to postpone age-related neurodegenerative diseases such as Alzheimer's disease. Stem cell therapy has also shown promise for improving regeneration and function of the aged or Alzheimer's disease brain. Several of these approaches are awaiting critical appraisal in clinical trials to determine their long-term efficacy and possible adverse effects. On the other hand, procedures such as intermittent fasting, physical exercise, intake of antioxidants such as resveratrol and curcumin have shown considerable promise for improving function in aging, some of which are ready for large-scale clinical trials, as they are non-invasive, and seem to have minimal side effects. In summary, several approaches are at the forefront of becoming mainstream therapies for combating aging and postponing age-related diseases in the coming years.

Intermittent Fasting (Alternate Day Fasting) in Healthy, Non-obese Adults: Protocol for a Cohort Trial with an Embedded Randomized Controlled Pilot Trial

BACKGROUND/OBJECTIVES

Alternate day fasting (ADF) is a subtype of intermittent fasting and is defined as a continuous sequence of a fast day (100% energy restriction, zero calories) and a feed day (ad libitum food consumption), resulting in roughly 36-h fasting periods. Previous studies demonstrated weight reductions and improvements of cardiovascular risk factors with ADF in obese subjects. However, rigorous data on potential endocrine, metabolic and cardiovascular effects, besides weight loss, are lacking. Therefore we aim to investigate the short- and mid- to long-term clinical and molecular effects of ADF in healthy non-obese subjects.

METHODS

We will perform a prospective cohort study with an embedded randomized controlled trial (RCT) including 90 healthy subjects. Thirty of them will have performed ADF for at least 6 months (mid-term group). Sixty healthy subjects without a particular diet before enrolment will serve as the control group. These subjects will be 1:1 randomized to either continuing their current diet or performing ADF for 4 weeks. All subjects will undergo study procedures that will be repeated in RCT participants after 4 weeks. These procedures will include assessment of outcome parameters, dual-energy X-ray absorptiometry, measurement of endothelial function, an oral glucose tolerance test, 24-h blood pressure measurement, retinal vessel analysis, echocardiography and physical activity measurement by an accelerometer. Blood, sputum, buccal mucosa and faeces will be collected for laboratory analyses. Participants in the RCT will wear a continuous glucose monitor to verify adherence to the study intervention.

PLANNED OUTCOMES

The aim of this project is to investigate the effects of ADF on human physiology and molecular cellular processes. This investigation should gain in-depth mechanistic insights into the concept of ADF and form the basis for larger subsequent cohort recruitment and consecutive intervention studies.

TRIAL REGISTRATION

NCT02673515; registered 24 November 2015. Current protocol date/version: 7 February 2017/version 1.8.

Intermittent Fasting with or without Exercise Prevents Weight Gain and Improves Lipids in Diet-Induced Obese Mice

Intermittent fasting (IF) and high intensity interval training (HIIT) are effective lifestyle interventions for improving body composition and overall health. However, the long-term effects of IF and potential synergistic effects of combining IF with exercise are unclear. The purpose of the study was to investigate the long-term effects of IF, with or without HIIT, on body composition and markers of metabolic health in diet-induced obese mice. In a randosmised, controlled design, 8-week-old C57BL/6 mice (males (n = 39) and females (n = 49)) were fed a high fat (HF) and sugar (S) water diet (30% (w/v)) for 24-weeks but were separated into five groups at 12-weeks: (1) 'obese' baseline control (OBC); (2) no intervention (CON); (3) intermittent fasting (IF); (4) high intensity intermittent exercise (HIIT) and (5) combination of dietary and exercise intervention (IF + HIIT). Body composition, strength and blood variables were measured at 0, 10 and/or 12-weeks. Intermittent fasting with or without HIIT resulted in significantly less weight gain, fat mass accumulation and reduced serum low density lipoproteins (LDL) levels compared to HIIT and CON male mice (p < 0.05). The results suggest that IF, with or without HIIT, can be an effective strategy for weight gain prevention despite concurrently consuming a high fat and sugar diet.

Metabolic Effects of Intermittent Fasting

The objective of this review is to provide an overview of intermittent fasting regimens, summarize the evidence on the health benefits of intermittent fasting, and discuss physiological mechanisms by which intermittent fasting might lead to improved health outcomes. A MEDLINE search was performed using PubMed and the terms "intermittent fasting," "fasting," "time-restricted feeding," and "food timing." Modified fasting regimens appear to promote weight loss and may improve metabolic health. Several lines of evidence also support the hypothesis that eating patterns that reduce or eliminate nighttime eating and prolong nightly fasting intervals may result in sustained improvements in human health. Intermittent fasting regimens are hypothesized to influence metabolic regulation via effects on (a) circadian biology, (b) the gut microbiome, and (c) modifiable lifestyle behaviors, such as sleep. If proven to be efficacious, these eating regimens offer promising nonpharmacological approaches to improving health at the population level, with multiple public health benefits.

Intermittent calorie restriction largely counteracts the adverse health effects of a moderate-fat diet in aging C57BL/6J mice

SCOPE

Calorie restriction (CR) has been shown to extend life- and health-span in model species. For most humans, a life-long CR diet is too arduous to adhere to. The aim of this study was to explore whether weekly intermittent CR can (1) provide long-term beneficial effects and (2) counteract diet-induced obesity in male aging mice.

METHODS AND RESULTS

In this study, we have exposed C57Bl/6J mice for 24 months to an intermittent (INT) diet, alternating weekly between CR of a control diet and ad libitum moderate-fat (MF) feeding. This weekly intermittent CR significantly counteracted the adverse effects of the MF diet on mortality, body weight, and liver health markers in 24-month-old male mice. Hepatic gene expression profiles of INT-exposed animals appeared much more comparable to CR- than to MF-exposed mice. At 12 months of age, a subgroup of MF-exposed mice was transferred to the INT diet. Gene expression profiles in the liver of the 24-month-old diet switch mice were highly similar to the INT-exposed mice. However, a small subset of genes was consistently changed by the MF diet during the first phase of life.

CONCLUSION

Weekly intermittent CR largely, but not completely, reversed adverse effects caused by a MF diet.