Form Of Intermittent Fasting Research Articles

Eight-hour time-restricted feeding improves endocrine and metabolic profiles in women with\xa0anovulatory polycystic ovary syndrome

BackgroundTime-restricted feeding (TRF) is a form of intermittent fasting, which is beneficial for weight loss and cardiometabolic health. Polycystic ovary syndrome (PCOS) is one of the most common reproductive endocrine and metabolic diseases affecting women of childbearing age. It is associated with an increased prevalence of metabolic syndrome, cardiovascular diseases and type 2 diabetes. The effects of TRF on PCOS patients remains undefined, here we investigated the impact of TRF on women with anovulatory PCOS.MethodsEighteen PCOS women aged between 18 and 31 with anovulation participated in a 6-week trial which were divided into two consecutive periods: (1) 1-week baseline weight stabilization period and (2) 5-week TRF period. Fifteen participants completed the study. Changes in body weight, body mass index (BMI), Waist-to-Hip Ratio, skeletal muscle mass, body fat mass (BFM), body fat percentage (BF%), visceral fat area (VFA), luteinizing hormone (LH), follicle-stimulating hormone (FSH), LH/FSH, total testosterone (TT), sex hormone-binding globulin (SHBG), free androgen index (FAI), fasting glucose, fasting insulin (FINS), homeostasis model assessment-insulin resistance (HOMA-IR), area under the curve (AUC) for insulin (AUCIns), area under the curve (AUC) for glucose (AUCGlu), AUCIns/AUCGlu Ratio, lipids, uric acid, alanine aminotransferase (ALT), aspartate aminotransferase, high-sensitivity C-reactive protein (hsCRP), insulin-like growth factor (IGF-1), menstrual cycle and eating behaviors were evaluated.ResultsSignificant changes in body weight, BMI, BFM, BF%, VFA, TT, SHBG, FAI, FINS, HOMA-IR, AUCIns, AUCIns/AUCGlu Ratio, ALT, hsCRP and IGF-1 were found after the TRF period. An improvement in menstrual cycle irregularity was detected in 73.3% (11/15) patients.ConclusionThe diet of TRF may be beneficial to anovulatory PCOS on weight loss especially reducing body fat, improving menstruation, hyperandrogenemia, insulin resistance and chronic inflammation.Trial registration Clinicaltrial.gov, NCT04580433, registered October 8, 2020, https://clinicaltrials.gov/ct2/show/NCT04580433.

Time-Restricted Eating to Improve Cardiovascular Health.

Time-restricted eating (TRE) is a form of intermittent fasting that involves confining the eating window to 4-10 h and fasting for the remaining hours of the day. The purpose of this review is to summarize the current literature pertaining to the effects of TRE on body weight and cardiovascular disease risk factors. Human trial findings show that TRE reduces body weight by 1-4% after 1-16 weeks in individuals with obesity, relative to controls with no meal timing restrictions. This weight loss results from unintentional reductions in energy intake (~350-500 kcal/day) that occurs when participants confine their eating windows to 4-10 h/day. TRE is also effective in lowering fat mass, blood pressure, triglyceride levels, and markers of oxidative stress, versus controls. This fasting regimen is safe and produces few adverse events. These findings suggest that TRE is a safe diet therapy that produces mild reductions in body weight and also lowers several key indicators of cardiovascular disease in participants with obesity.

Intermittent fasting for obesity and related disorders: unveiling myths, facts, and presumptions.

Intermittent fasting (IF) is an increasingly popular method of weight loss, as an alternative to daily caloric restriction (DCR). Several forms of IF exist, such as alternate-day fasting or time-restricted feeding regimens. Some of its proponents claim several health benefits unrelated to caloric restriction or weight loss, which rely mainly on animal models. Although several studies published in the last few years confirm that IF can be a useful and safe therapeutical option for obesity and related disorders, no superiority to conventional caloric restriction diets have emerged. There are still several questions left answered. In this Review, we discuss some of the claims, unveiling myths, facts, and presumptions about several models of IF. The focus of this article is obesity, but there is a brief discussion of the potential benefits of IF on overall human health.

PENGARUH TIME RESTRICTED FEEDING (TRF) TERHADAP PENURUNAN TEKANAN DARAH PASIEN HIPERTENSI

Hypertension is a chronic condition characterized by an increase in systolic blood pressure> 140 mmHg and diastole> 90 mmHg. This condition can damage blood vessels and interfere with blood flow, causing degenerative diseases to death. Time Restricted Feeding (TRF) is a form of intermittent fasting that regulates eating patterns by applying a cycle model of 12-16 hours of fasting and another 8-12 hours of non-fasting. TRF fasting follows the circadian rhythm pattern of the human body light-dark (eat-fast). This study aims to determine the effect of TFR on reducing blood pressure in hypertensive patients. This research is a quantitative study using a quasy experimental design with a non-equivalent control group approach, with the population being hypertensive patients living in 2 and 5 neighborhoods of Helvetia Village, sampling by means of purposive sampling with 32 respondents divided into intervention and control groups. . Respondents did TRF fasting for 30 days with a span of 12 hours of fasting starting after dinner while still allowed to drink mineral water. There are no restrictions on calories or types of food when the respondent is not fasting. The results of the study after the Wilcoxon test showed that systolic blood pressure in the intervention group decreased by 11.12 mmHg with a value of p = 0.003 (p <0.05) and diastolic blood pressure decreased by 5.19 mmHg with a value of p = 0.003 (<0.05) compared to the control group. TRF fasting follows the circadian rhythm pattern of the human body light-dark (eat-fast) so it is very good for people with hypertension The conclusion of this study is that there is an effect of TRF fasting on lowering blood pressure in hypertensive patients.

The Effects of Intermittent Fasting Combined with Resistance Training on Lean Body Mass: A Systematic Review of Human Studies.

Diets utilising intermittent fasting (IF) as a strategic method to manipulate body composition have recently grown in popularity, however, dietary practices involving fasting have also been followed for centuries for religious reasons (i.e., Ramadan). Regardless of the reasons for engaging in IF, the impacts on lean body mass (LBM) may be detrimental. Previous research has demonstrated that resistance training promotes LBM accrual, however, whether this still occurs during IF is unclear. Therefore, the objective of this review is to systematically analyse human studies investigating the effects of variations of IF combined with resistance training on changes in LBM in previously sedentary or trained (non-elite) individuals. Changes in body weight and fat mass, and protocol adherence were assessed as a secondary objective. This review followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. MEDLINE, CINAHL, PubMed and SportDiscus databases were searched for articles investigating IF, combined with resistance training that reported measures of body composition. Eight studies met the eligibility criteria. LBM was generally maintained, while one study reported a significant increase in LBM. Body fat mass or percentage was significantly reduced in five of eight studies. Results suggest that IF paired with resistance training generally maintains LBM, and can also promote fat loss. Future research should examine longer-term effects of various forms of IF combined with resistance training compared to traditional forms of energy restriction. Prospero registration CRD42018103867.

The Impact of Time-Restricted Feeding on Exercise-Induced Immune Parameters in C57BL/6 Male Mice

Abstract Objectives Food intake and exercise are considered modulators of the immune system. Specifically, intermittent fasting protocols have been demonstrated to reduce inflammation and alter cytokine responses. The objective of the current study was to determine if a form of intermittent fasting known as time-restricted feeding (TRF) would alter immune parameters in response to exercise. Methods 8-week-old C57BL/6 male mice were divided into three groups based on feeding schedule; group one had access to food ad libitum (Control) and groups two and three had access to food in a time restricted manner. Access was allowed for six hours per day either immediately after running (TRF-imm) or six hours after running (TRF-del). Mice ran on a treadmill for 1 hour, 5 days per week for eight weeks. Diet consisted of 21% protein, 16% fat and 64% carbohydrate. Weight, glucose and ketone levels, and immune populations were analyzed. Systemic IL-6 and TNF-α levels were measured before and after running. In a subpopulation, cytokine response to lipopolysaccharides (LPS) was also monitored. Results All mice gained weight during the eight-week intervention, but TRF-imm gained significantly less weight than Control (P = 0.02). No differences were detected in glucose levels. The ketone body β-hydroxybutyrate (BHB) was significantly higher at week eight in TRF groups (P ≤ 0.03) but running induced BHB in all groups to approximately 1 mM. Running reduced the blood lymphocytes levels (P < 0.05), with a concomitant increase of granulocytes (P < 0.05) in all groups. There was a small increase in monocytes only in the Control group (P = 0.017). No differences were detected in splenic immune populations, including CD4 and CD8 T cells, and CD11b + cells. Both IL-6 and TNF-α levels were low in all groups before exercise; however, post exercise IL-6 was increased, but not to the same extend in all groups. The IL-6 response was blunted in the TRF groups. The reduced levels of IL-6 was not due to loss of immune function, as both IL-6 and TNF-α were readily induced by exposure of mice to LPS. Conclusions Time-restricted feeding protocols did not induce differences in immune cell composition in blood or spleen but resulted in attenuated exercise-induced IL-6 levels. Funding Sources University of Memphis, School of Health Studies.

The Effect of 6- h and 8-h Time Restricted Feeding on Body Weight, Glucoregulatory Factors, IGF-1 and IGFBP-3 in Adults with Obesity

Abstract Objectives Time restricted feeding is a novel approach to intermittent fasting which includes a 6–10 hour feeding window and a 14–18 hour fasting window daily. Some forms of intermittent fasting have resulted in improvement in IGF-1 and IGFBP-3 in mice. These factors may affect cancer risk and cancer progression after diagnosis. However, effect in humans remains unknown. This exploratory analysis examined the effect of 12 weeks of 8-hour time-restricted feeding (10:00–18:00) and 8 weeks of 6-hour time-restricted feeding (12:00–18:00) versus a control in adults with obesity. Methods Participants with obesity (n = 24) participated in either an 8-h time restricted feeding intervention (ad libitum feeding between 10:00–6:00 pm) for 12 weeks or a 6-h time restricted feeding intervention (ad libitum feeding between 1:00–700 pm) for 8 weeks. Data for two time-restricted feeding trials were combined for this exploratory analysis and compared to a no intervention control group with obesity (n = 8). Weight loss, glucose regulatory factors, IGF-1 and IGFBP3 were measured. Results Body weight decreased significantly more in the 6-h (−2.82 ± 0.05 kg) and the 8-h (−2.77 ± 0.50 kg) groups than the controls (p < 0.001). Fat mass decreased significantly more in the 6-h (−1.5 ± 0.2 kg) and the 8-h (−1.5 ± 0.4 kg) groups than the controls (p = 0.016). Lean mass decreased significantly more in the 6-h group (−1.8 ± 0.2 kg) than the 8-h (p = .005) and the controls (p = .004). HOMA-IR decreased significantly more in the 8-h group (−0.3 ± 0.1 units) than the control group (p = 0.38). There was no difference in HOMA-IR (measure of insulin resistance) between the 6-h group (−.01 ± 0.3 units) and either the 8-h or the control groups (p = 0.91 and p = 0.86). Fasting insulin decreased significantly more in the 8-h group (−1.2 ± 0.6 uIU/ml) than control group (p = .033). There was no difference in change in insulin between the 8-h and 6-h groups (p = .952). No changes were seen in glucose, IGF-1 (8-h: −3.04 ± 13.49 ng/mL, 6-h: −0.42 ± 16.96 ng/mL) or IGFBP-3 (8-h: 0.17 ± 0.15 ng/mL, 6-h: 0.18 ± 0.07 ng/mL). Conclusions These findings suggest that 6-h and 8-h time-restricted feeding produce mild weight and fat loss as well as glucoregulatory improvement. It is unclear if time restricted feeding effects the cancer promoting biomarkers, IGF-1 and IGFBP3. Funding Sources University of Illinois at Chicago.

MON-606 Changes in Eating Frequency but Not in Food Quality During Time Restricted Eating: Analysis from the See Food Study

Time-restricted eating (TRE) is a form of intermittent fasting that has gained interest in nutrition research and interventions as one of the dietary patterns to promote weight loss and other metabolic benefits. TRE is an eating pattern in which all nutrient intakes occur within a few hours (< 12 hours) every day, with no overt attempt to alter nutrient quality or quantity. The “See Food” study was a randomized, unblinded, controlled, behavioral interventional pilot clinical trial conducted from 2017-2018, that aimed to study the effect of a TRE intervention on metabolic health of overweight and obese participants, using the help of novel digital mobile technology. The objective of the current study is to analyze changes in diet quality among participants of the “See Food” study. Specifically, food intake patterns (frequency and type of meals, snacks and beverages) were compared between subjects in the 8-hour TRE intervention group, versus the unrestricted intake control group. Inclusion criteria included age 18-65, BMI >25 kg/m2, had stable sleep and work schedule and owned a smartphone. Participants with diabetes, cardiovascular disease, uncontrolled pulmonary disease, pregnancy and nursing were excluded. A total of 20 participants with overweight or obesity (9 in control group and 11 in TRE group) were enrolled. Participants were instructed to use the “myCircadianClock” smartphone application to document their time of eating, type of meal and food images at baseline and during the intervention period of 14 weeks. The TRE group was instructed to consume calories within 8 hours each day. We compared the data between 14 days at baseline and 14 days at the end of the intervention. An eating occasion (EO) as defined as an occasion when a food or beverage (other than water) was consumed, and was separate from another EO by at least 15 minutes. Compared to baseline, both the TRE (3.8±0.4 vs 5.3±0.4, p<0.0001) and control group (4.9±0.4 vs 5.6±0.5, p=0.007) had less eating frequency. The TRE group had less eating frequency compared to control group (-1.5±0.2 vs -0.6±0.2, p=0.01) at the end of the study. Meal quality was classified by meal or snack type using a food-based classification system, and included 6 Eos ranging from a complete meal, to a low-quality snack. Beverages were classified separately by type. There were no differences in meal quality between the TRE and control group. The TRE group had less frequency of high-quality snack (-0.5±0.1 vs 0.05±0.1, p=0.008), mixed quality snack (-0.03±0.06 vs -0.3±0.07, p=0.01) and caffeinated beverage (-0.6±0.09 vs -0.008±0.1) compared to the control group. Conclusions: There was a reduction in eating frequency but no change in food quality when following an 8-hour TRE. Estimation of calories intake was limited in this study. A strength of the study is the use of a novel mobile app to track timing of meals. This would be feasible to implement in a real life setting.

Effect of time restricted feeding on the gut microbiome in adults with obesity: A pilot study.

Time restricted feeding is a form of intermittent fasting where participants shorten the daily window in which they eat. This is the first study to examine the effects of intermittent fasting on changes in the gut microbiome. Adults with obesity (n = 14) participated in a daily 8-hour time restricted feeding intervention (8-hour feeding window/16-hour fasting window) for 12 weeks. Fecal microbiota were determined by 16 S rRNA (ribosomal ribonucleic acid) gene sequencing of stool samples. Body weight decreased (P < 0.05) by -2 ± 1 kg. Gut microbiota phylogenetic diversity remained unchanged. The two most common phyla were Firmicutes and Bacteroidetes accounting for 61.2% and 26.9% of total abundance at baseline. No significant alterations in the abundance of Firmicutes, Bacteroidetes, or any other phyla were detected after 12 weeks of time restricted feeding. Time restricted feeding did not significantly alter the diversity or overall composition of the gut microbiome.

Intermittent Fasting Could Be Safely Achieved in People With Type 1 Diabetes Undergoing Structured Education and Advanced Glucose Monitoring.

Background: Fasting during Ramadan is a form of intermittent fasting in which a person abstains from oral intake between the hours of sunrise and sunset. The fasting month of Ramadan is observed by Muslims worldwide. People with type 1 diabetes (T1DM) who choose to fast during Ramadan are at a particularly high risk of acute diabetes complications including hypoglycemia and significant hyperglycemia. We hypothesized that people with uncomplicated T1DM would be able to fast safely during Ramadan following structured education and with daily advanced glucose monitoring.Methods: People with stable and uncomplicated T1DM treated with multiple daily injections (MDIs) or continuous subcutaneous insulin infusion (CSII) who chose to fast during Ramadan were recruited for the study. Participants attended Dose Adjustment for Normal Eating (DAFNE) structured education training, and basal insulin was reduced in a controlled fashion. Participants were assigned a sensor-augmented insulin pump or FreeStyle Libre for advanced glucose monitoring. The primary endpoint was the rate of hypoglycemia during Ramadan compared to before Ramadan. Secondary endpoints were percentage time spent <4 mmol/L, >10 mmol/L (range, 4–10 mmol/L), episodes of diabetic ketoacidosis (DKA), and acute kidney injury or hospitalization for any cause.Results: Rates of hypoglycemia were significantly reduced during Ramadan compared with rates before Ramadan (0.53 ± 0. 49 vs. 0.81 ± 0.69 episodes/day, p = 0.0015). No episodes of severe hypoglycemia, DKA, acute kidney injury, or hospitalization occurred during Ramadan period. Percentage time spent >10 mmol/L (46.7 ± 17.7% vs. 42.5 ± 16.4%, p = 0.03) was significantly increased, and percentage time [range, 4–10 mmol/L (48.8 ± 15.9% vs. 50.9 ± 15.9%, p = 0.13)] and percentage time spent <4 mmol/L (4.7 ± 5.4.7% vs. 5.7 ± 6.3%, p = 0.09) were reduced, but these differences were not significant.Conclusions: People with uncomplicated T1DM could safely participate in intermittent fasting similar to Ramadan fasting if equipped with structured education and advanced glucose monitoring systems.

A Randomised Controlled Trial on the Effectiveness and Adherence of Modified Alternate-day Calorie Restriction in Improving Activity of Non-Alcoholic Fatty Liver Disease

Currently, there is no effective therapy for non-alcoholic fatty liver disease (NAFLD), and although calorie restriction is recommended in guidelines, but adherence is an issue. The current study aimed to determine the effectiveness of eight weeks intermittent fasting (IF) strategy in the control of NAFLD activity and the adherence rate of such strategy. This was a randomized controlled trial with modified alternate-day calorie restriction (MACR), a form of IF, as the active intervention and usual habitual diet as control. The outcome measures included changes in body mass index (BMI), blood lipids (cholesterol, LDL, HDL and triglyceride), fasting blood sugar (FBS), liver enzymes (ALT and AST), and ultrasound measurements of liver steatosis and 2-dimensional shear wave elastography (SWE). Per-protocol (PP) analysis was performed with comparison within (post vs. pre-intervention) and between (MACR vs. control) groups and P < 0.05 as significant. Of 115 individuals with NAFLD, 43 satisfied the study entry criteria, and 33 were randomised to MACR and 10 to control group, and after 8 weeks, 30 from MACR and 9 from control group completed PP. Significant reduction in weight and BMI (P = 0.001 and 0.02 respectively) was observed in MACR vs. control. Likewise, ALT was reduced with MACR but not control (P = 0.02). No reductions in lipid parameters and FBS were found in between-group analyses (all P > 0.22). Both liver steatosis and fibrosis (SWE) scores were significantly reduced in MACR vs. controls (both P < 0.01). Adherence level for MACR remained between 75-83% throughout the study. As a conclusion, eight weeks of IF (MACR) strategy appears more effective than usual habitual diet in the control of NAFLD activity and with good adherence rate.

Early Time-Restricted Feeding Improves 24-Hour Glucose Levels and Affects Markers of the Circadian Clock, Aging, and Autophagy in Humans.

Time-restricted feeding (TRF) is a form of intermittent fasting that involves having a longer daily fasting period. Preliminary studies report that TRF improves cardiometabolic health in rodents and humans. Here, we performed the first study to determine how TRF affects gene expression, circulating hormones, and diurnal patterns in cardiometabolic risk factors in humans. Eleven overweight adults participated in a 4-day randomized crossover study where they ate between 8 am and 2 pm (early TRF (eTRF)) and between 8 am and 8 pm (control schedule). Participants underwent continuous glucose monitoring, and blood was drawn to assess cardiometabolic risk factors, hormones, and gene expression in whole blood cells. Relative to the control schedule, eTRF decreased mean 24-hour glucose levels by 4 ± 1 mg/dl (p = 0.0003) and glycemic excursions by 12 ± 3 mg/dl (p = 0.001). In the morning before breakfast, eTRF increased ketones, cholesterol, and the expression of the stress response and aging gene SIRT1 and the autophagy gene LC3A (all p < 0.04), while in the evening, it tended to increase brain-derived neurotropic factor (BNDF; p = 0.10) and also increased the expression of MTOR (p = 0.007), a major nutrient-sensing protein that regulates cell growth. eTRF also altered the diurnal patterns in cortisol and the expression of several circadian clock genes (p < 0.05). eTRF improves 24-hour glucose levels, alters lipid metabolism and circadian clock gene expression, and may also increase autophagy and have anti-aging effects in humans.

Energy Metabolism and Intermittent Fasting: The Ramadan Perspective.

Intermittent fasting (IF) has been gaining popularity as a means of losing weight. The Ramadan fast (RF) is a form of IF practiced by millions of adult Muslims globally for a whole lunar month every year. It entails a major shift from normal eating patterns to exclusive nocturnal eating. RF is a state of intermittent liver glycogen depletion and repletion. The earlier (morning) part of the fasting day is marked by dominance of carbohydrate as the main fuel, but lipid becomes more important towards the afternoon and as the time for breaking the fast at sunset (iftar) gets closer. The practice of observing Ramadan fasting is accompanied by changes in sleeping and activity patterns, as well as circadian rhythms of hormones including cortisol, insulin, leptin, ghrelin, growth hormone, prolactin, sex hormones, and adiponectin. Few studies have investigated energy expenditure in the context of RF including resting metabolic rate (RMR) and total energy expenditure (TEE) and found no significant changes with RF. Changes in activity and sleeping patterns however do occur and are different from non-Ramadan days. Weight changes in the context of Ramadan fast are variable and typically modest with wise inter-individual variation. As well as its direct relevance to many religious observers, understanding intermittent fasting may have implications on weight loss strategies with even broader potential implications. This review examines current knowledge on different aspects of energy balance in RF, as a common model to learn from and also map out strategies for healthier outcomes in such settings.

The role of intermittent fasting and meal timing in weight management and metabolic health.

Obesity remains a major public health concern and intermittent fasting is a popular strategy for weight loss, which may present independent health benefits. However, the number of diet books advising how fasting can be incorporated into our daily lives is several orders of magnitude greater than the number of trials examining whether fasting should be encouraged at all. This review will consider the state of current understanding regarding various forms of intermittent fasting (e.g. 5:2, time-restricted feeding and alternate-day fasting). The efficacy of these temporally defined approaches appears broadly equivalent to that of standard daily energy restriction, although many of these models of intermittent fasting do not involve fed-fasted cycles every other 24 h sleep-wake cycle and/or permit some limited energy intake outside of prescribed feeding times. Accordingly, the intervention period therefore may not regularly alternate, may not span all or even most of any given day, and may not even involve absolute fasting. This is important because potentially advantageous physiological mechanisms may only be initiated if a post-absorptive state is sustained by uninterrupted fasting for a more prolonged duration than applied in many trials. Indeed, promising effects on fat mass and insulin sensitivity have been reported when fasting duration is routinely extended beyond sixteen consecutive hours. Further progress will require such models to be tested with appropriate controls to isolate whether any possible health effects of intermittent fasting are primarily attributable to regularly protracted post-absorptive periods, or simply to the net negative energy balance indirectly elicited by any form of dietary restriction.

SAT-336 Time Restricted Feeding Delays Breast Cancer Initiation and Growth in a Mouse Model of Postmenopausal Obesity

Background: The prevalence of obesity and the metabolic syndrome (MetS) has increased dramatically in developed countries over the last three decades (Flegal et al., 2012). Numerous studies indicate that adiposity and the MetS are independent risk factors for multiple diseases including cancer, particularly postmenopausal breast cancer (Kim et al., 2018). Therefore improving the metabolic health of obese postmenopausal women may mitigate their risk for breast cancer. Accumulating evidence suggests that time-restricted feeding (TRF), a form of intermittent fasting in which food intake is limited to a defined period during the normal active phase, can have a positive influence on metabolic health. Importantly, interventional studies in obese mice and small clinical studies in humans have demonstrated that TRF can improve metabolic health even though obesity is maintained (Sutton et al., 2018). Time restriction rather than calorie restriction is thus a promising method to control the negative sequelae of obesity, due to the hunger and irritability that reduces compliance with long-term calorie restriction. The objective of this study was to investigate whether TRF attenuates breast cancer in a mouse model of postmenopausal obesity and whether this effect is mediated by reducing the hyperinsulinemia associated with obesity. Methods: Ovariectomized mice were used as postmenopausal mice model. The ovariectomized mice were initially made obese by feeding 60% high fat diet (HFD) for 10 weeks and then grouped into a continued ad libitum group (24 h access to food) or a TRF group (8 h access to food during active phase). For an orthotopic tumor model, mice were injected with E0771 breast cancer cells into four mammary fat pads per mouse three weeks following the start of TRF. As a tumor initiation model, transgenic PyMT mice were used to assess tumor onset and growth following the same TRF or AL access to the HFD. The insulin dependency of tumor growth was studied by increasing insulinemia using an implanted insulin pump, or by reducing insulin secretion using diazoxide. Insulin effects on tumor cell proliferation and migration was further validated in vitro. Results and Conclusion: TRF had a dramatic effect, reducing tumor growth in obese mice fed a high fat diet (HFD) to levels seen in lean mice. Tumor growth and initiation was also delayed in the transgenic PyMT model of mammary tumorigenesis. Our results further suggest that the antitumor effect of TRF is at least partially mediated by reducing hyperinsulinemia, suggesting that this intervention may be effective in breast cancer prevention and therapy.

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Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes

Intermittent fasting (IF) improves cardiometabolic health; however, it is unknown whether these effects are due solely to weight loss. We conducted the first supervised controlled feeding trial to test whether IF has benefits independent of weight loss by feeding participants enough food to maintain their weight. Our proof-of-concept study also constitutes the first trial of early time-restricted feeding (eTRF), a form of IF that involves eating early in the day to be in alignment with circadian rhythms in metabolism. Men with prediabetes were randomized to eTRF (6-hr feeding period, with dinner before 3 p.m.) or a control schedule (12-hr feeding period) for 5weeks and later crossed over to the other schedule. eTRF improved insulin sensitivity, β cell responsiveness, blood pressure, oxidative stress, and appetite. We demonstrate for the first time in humans that eTRF improves some aspects of cardiometabolic health and that IF's effects are not solely due to weight loss.

Intermittent food restriction initiated late in life prolongs lifespan and retards the onset of age-related markers in the annual fish Nothobranchius guentheri.

Two of the most studied and widely accepted conjectures on possible aging mechanisms are the oxidative stress hypothesis and the insulin/insulin-like growth factor 1 (IGF-1) signaling (IIS) pathway. Intermittent fasting (IF) is known to modulate aging and to prolong lifespan in a variety of organisms, but the mechanisms are still under debate. In this study, we first demonstrated that late-onset two consecutive days a week fasting, a form of IF, termed intermittent food restriction (IFR), exhibited a time-dependent effect, and long-term late-onset IFR extended the mean lifespan and maximum lifespan by approximately 3.5 and 3weeks, respectively, in the annual fish Nothobranchius guentheri. We also showed that IFR reduced the accumulation of lipofuscin in the gills and the protein oxidation and lipid peroxidation levels in the muscles. Moreover, IFR was able to enhance the activities of antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase in the fish. Finally, IFR was also able to decelerate the decrease of SirT1 and Foxo3A, but accelerate the decrease of IGF-1. Collectively, our findings suggest that late-onset IFR can retard the onset of age-related markers, and prolong the lifespan of the aging fish, via a synergistic action of an anti-oxidant system and the IIS pathway. It also proposes that the combined assessment of anti-oxidant system and IIS pathway will contribute to providing a more comprehensive view of anti-aging process.

Variation in Individual Responses to Time-Restricted Feeding and Resistance Training

Time-restricted feeding (TRF) is a form of intermittent fasting which limits all caloric intake to a certain period of time each day in an attempt to reduce daily energy intake, promote weight loss, and improve health. Resistance training (RT) has been reported to increase muscular strength and improve body composition. Very limited information is available on the combination of TRF and RT. PURPOSE: To examine the variation in individual body composition, dietary intake, and muscular performance responses to an 8-wk TRF and RT program. METHODS: Healthy males (n = 20; age = 22 ± 3 y; BMI = 27 ± 6 kg/m2; % fat = 22 ± 6 % wt) were randomized to TRF + RT or RT alone for 8 wks. RT was performed 3 dys/wk and consisted of alternate workouts of upper and lower body using a resistance progression scheme. TRF limited energy intake to a 4-hr period on the 4 dys/wk when RT was not performed. Energy intake was not restricted in either group, and eating times were not specified in the RT alone group. Body composition, muscular performance, and dietary records were assessed at 0, 4, and 8 wks. Inter- and intra-individual variations in outcome measures were estimated by hierarchical linear growth modeling. The amount of variability attributable to characteristics between or within participants was evaluated from variance estimates. RESULTS: For TRF + RT, percent changes ranged from -5.5 to +2.6% for body weight, -22.1 to +9.4% fat mass, -7.7 to +4.6% for lean body mass, +3.4 to +30.4% for bench press 1-RM, and +10.1 to +67.6% for leg press 1-RM. For RT alone, percent changes ranged from -6.6 to +2.1% for body weight, -14.4 to +12.6% for fat mass, -4.1 to +3.9% for lean body mass, +4.9 to +12.9% for bench press 1-RM, and +14.3 to +37.7% for leg press 1-RM. Percentages of total variability attributed to inter-individual factors ranged from 3.3 to 49.2% for dietary measures, 59.0 to 93.9% for muscular performance, and 97.0 to 99.6% for body composition. Remaining variability was attributed to intra-individual factors. CONCLUSION: Individual responses to the study interventions varied widely. Differences between individuals were an important source of variability, indicating participant samples should be homogenous and/or quite large to examine changes in body composition or muscular performance using nutrition and exercise interventions.

Intermittent fasting combined with resistance training: effects on body composition, muscular performance, and dietary intake

Background Intermittent fasting (IF) is a dietary strategy that has recently gained popularity due to a number of potential health benefits. One form of IF, termed time-restricted feeding (TRF), only allows caloric intake during a limited window of time each day (often 4 to 8 hours in duration). One concern of IF is the potential loss of lean mass due to the fasting periods. Resistance training is known to help mitigate loss of lean mass during hypocaloric diets. The purpose of this experiment was to examine the effects of TRF in combination with resistance training on body composition, muscular performance, and dietary intake in young untrained males.