Intermittent Diet Research Articles

Glutathione peroxidase 3 is essential for countering senescence in adipose remodelling by maintaining mitochondrial homeostasis

Adipose tissue senescence is a precursor to organismal aging and understanding adipose remodelling contributes to discovering novel anti-aging targets. Glutathione peroxidase 3 (GPx3), a critical endogenous antioxidant enzyme, is diminished in the subcutaneous adipose tissue (sWAT) with white adipose expansion. Based on the active role of the antioxidant system in counteracting aging, we investigated the involvement of GPx3 in adipose senescence. We determined that knockdown of GPx3 in adipose tissue by adeno-associated viruses impaired mitochondrial function in mice, increased susceptibility to obesity, and exacerbated adipose tissue senescence. Impairment of GPx3 may cause mitochondrial dysfunction through inner mitochondrial membrane disruption. Adipose reshaping management (cold stimulation and intermittent diet) counteracted the aging of tissues, with an increase in GPx3 expression. Overall metabolic improvement induced by cold stimulation was partially attenuated when GPx3 was depleted. GPx3 may be involved in adipose browning by interacting with UCP1, and GPx3 may be a limiting factor for intracellular reactive oxygen species (ROS) accumulation during stem cell browning. Collectively, these findings emphasise the importance of restoring the imbalanced redox state in adipose tissue to counteract aging and that GPx3 may be a potential target for maintaining mitochondrial homeostasis and longevity.

Manchester Intermittent Diet in Gestational Diabetes Acceptability Study (MIDDAS-GDM): a two-arm randomised feasibility protocol trial of an intermittent low-energy diet (ILED) in women with gestational diabetes and obesity in Greater Manchester

IntroductionThe prevalence of gestational diabetes mellitus (GDM) is rising in the UK and is associated with maternal and neonatal complications. National Institute for Health and Care Excellence guidance advises first-line...

Association of Christian Orthodox Fasting with Sociodemographic, Anthropometric and Lifestyle Factors and Serum Biochemical Indices: A Cross-Sectional Study on Patients with Metabolic Diseases.

Christian Orthodox fasting, a type of time-restricted diet, which presents some similarities to the Mediterranean Diet, also including certain similarities with periodic vegetarianism or other time-restricted diets (e.g., intermittent diet and Ramadan fasting), may cumulatively be related to the same or even better beneficial healthy effects as these well-recognized dietary patterns. The present study aimed to explore the potential beneficial impact of Christian Orthodox fasting in patients with metabolic disorders, such as diabetes mellitus type 2, excessive obesity, hypothyroidism and osteoporosis. This was a cross-sectional study, including 135 patients with metabolic disorders (67 fasters and 68 non-fasters). The enrolled fasters had adapted Christian Orthodox fasting recommendations for at least twelve consecutive years or even from childhood. Relevant questionnaires were used to record sociodemographic, anthropometric and lifestyle data of the study population through face-to-face interviews between the enrolled individuals and qualified personnel during a non-fasting period. Christian Orthodox fasting patients showed a significantly and independently lower prevalence of overweight/obesity and abdominal obesity, which is highly associated with cardiometabolic disease risks, as well as a significantly and independently lower incidence of hypertension, including separately lower systolic and diastolic pressure, than non-fasting patients. Fasters also had a significantly and independently increased prevalence of an advanced educational level and no smoking history, as well as a lower incidence of sedentary behavior, and a trend of a correlation with reduced c-reactive protein (CRP), an indicator of inflammation, compared to non-fasters. Fasters also exhibited higher serum albumin and high-density lipoprotein (HDL) levels, as well as lower glucose levels, than non-fasters. This is one of the few cross-sectional studies demonstrating that Christian Orthodox fasting may promote metabolic health by improving several aspects of metabolic disorders, being associated with specific sociodemographic, anthropometric and lifestyle factors. Further studies conducted on larger sample sizes from different countries and different ethnicities that include Christian Orthodox fasters are recommended to evaluate the impact of long-term religious fasting effects on human health, either as a preventative factor reducing the risk of chronic diseases and especially cardiometabolic disorders or as a nutritional intervention to ameliorate symptom severity.

Effects of intermittent dieting with break periods on body composition and metabolic adaptation: a systematic review and meta-analysis.

Intermittent dieting incorporated with break periods (INT-B) has recently been promoted as an alternative dietary approach for optimal weight management. This study assessed the effectiveness of INT-B compared with that of conventional continuous energy restriction (CER) for improving body composition and attenuating metabolic adaptation. A systematic search was conducted on 6 databases using all available records until July 2023. The extracted data included the lead author, year of publication, population characteristics, intervention protocols, duration, and adherence. Random-effects meta-analyses were conducted for within-group and between-group comparisons of anthropometric and metabolic outcomes. Subgroup moderator analysis was performed for the types of INT-B, intervention duration, and population characteristics. Of the 1469 records, 12 randomized trials (with 881 participants) were included. Within-group analyses demonstrated significant improvements in body mass, fat mass, body mass index, body fat percentage, and waist circumference following both INT-B and CER, with no significant group differences. However, resting metabolic rate (RMR) was significantly reduced following CER only. The compensatory reduction in RMR was significantly smaller following INT-B compared with CER, suggesting a lesser degree of metabolic adaptation. INT-B had a more significant effect on RMR retention in individuals with overweight/obesity compared with resistance-trained individuals. This review provides up-to-date evidence for INT-B as a viable dietary strategy to improve body composition and attenuate metabolic adaptation. PROSPERO registration no. CRD42023448959.

Effects of Different Types of Intermittent Fasting on Obesity, Inflammation, and T2DM

Currently, there is much discussion on how to deal with the increasing trend of becoming overweight and the chronic diseases it is associated with. Obesity and its associated chronic diseases are a big concern in modern living. It has been discovered that intermittent fasting, may be a practical solution to this problem. As this potential solution has yielded positive results for patients who have been enrolled in obesity medical studies. This paper principal goal will be to collect and analyzed the research data related to type 2 diabetes (T2DM), obesity and intermittent fasting, and explore whether intermittent diet has a positive impact on the cure of obesity and related diseases. Research has found that various intermittent diets have a positive impact on weight control, especially the ADF diet. Although participants may experience some adverse reactions during intermittent eating, the impact is not significant, and the vast majority of participants can persist until the end of the experiment and achieve good results. Although intermittent diet has no significant effect on the intervention of inflammation, its intervention on type 2 diabetes, is effective and long-lasting. Overall, intermittent fasting is more effective in intervening and treating obesity and related chronic diseases compared to traditional therapies and may have a more widespread promotion in the future.

Role of insulin resistance and leptin in the effect of intermittent feeding with a high-protein ketogenic diet on body composition in rats

ObjectivesThe prevalence of obesity and overweight in children has been increasing rapidly worldwide and threatens society with various chronic diseases that these children are born with. High-protein ketogenic diets and intermittent nutrition are thought to be protective against obesity and metabolic syndrome MetS. However, the exact effects and results, insulin resistance, and the role of leptin in the functioning mechanism of these diets have not been fully elucidated. The aim of this study was to investigate the roles of insulin resistance and leptin hormone on the effects of body composition with a high-protein ketogenic diet and intermittent nutrition combination. MethodsThirty-two young non-obese rats were randomly divided into four equal groups. Both the standard diet and the high-protein ketogenic diet were given ad libitum and intermittently to the rats for 6 wk. The body weight and fat mass of the rats were measured at the end of the experiment. The fasting glucose, leptin, insulin, high- and low-density lipoprotein, and triacylglycerols were measured with the blood samples. ResultsThe lowest body weight was observed in the intermittent and high-protein ketogenic diet group, followed by the free high-protein ketogenic diet and standard intermittent diet group, respectively. Also, the lowest body fat mass was observed in the intermittent and high-protein ketogenic diet group, followed by the standard intermittent diet group. Although there was no change in leptin, insulin, high- and low-density lipoprotein, and triacylglycerol levels in any group, the lowest blood glucose rate was observed in the intermittent and high-protein ketogenic diet group. ConclusionThe results of the present study revealed that an intermittent high-protein ketogenic diet is more effective than others in weight loss without disrupting biochemical health parameters, and the applied diets do not prevent growth and development.

A Comparative Perspective Between Calorie Restriction with Behavioral Determinants and Other Models Such as Intermittent Dieting, Nutrient Timing, Chronotypes and Macronutrient Adjustment in the Weight Loss Process

A Comparative Perspective Between Calorie Restriction with Behavioral Determinants and Other Models Such as Intermittent Dieting, Nutrient Timing, Chronotypes and Macronutrient Adjustment in the Weight Loss Process

The Effects of Intermittent Diet Breaks during 25% Energy Restriction on Body Composition and Resting Metabolic Rate in Resistance-Trained Females: A Randomized Controlled Trial.

The purpose of this study was to examine the effects of intermittent versus continuous energy restriction on body composition, resting metabolic rate, and eating behaviors in resistance-trained females. Thirty-eight resistance-trained females (mean ± standard deviation age: 22.3 ± 4.2 years) were randomized to receive either six weeks of a continuous 25% reduction in energy intake (n = 18), or one week of energy balance after every two weeks of 25% energy restriction (eight weeks total; n = 20). Participants were instructed to ingest 1.8 g protein/kilogram bodyweight per day and completed three weekly supervised resistance training sessions throughout the intervention. There were no differences between groups for changes over time in body composition, resting metabolic rate, or seven of the eight measured eating behavior variables (p > 0.05). However, a significant group-by-time interaction for disinhibition (p < 0.01) from the Three-Factor Eating Questionnaire was observed, with values (± standard error) in the continuous group increasing from 4.91 ± 0.73 to 6.17 ± 0.71, while values in the intermittent group decreased from 6.80 ± 0.68 to 6.05 ± 0.68. Thus, diet breaks do not appear to induce improvements in body composition or metabolic rate in comparison with continuous energy restriction over six weeks of dieting, but may be employed for those who desire a short-term break from an energy-restricted diet without fear of fat regain. While diet breaks may reduce the impact of prolonged energy restriction on measures of disinhibition, they also require a longer time period that may be less appealing for some individuals.

Comparison of Sleep Quality and Quality of Life Before and During Ramadan Fasting Among Healthy Adult Population in Kuala Nerus, Terengganu

Ramadan is a tenet of Islam and requires four weeks of continuous fasting during daylight hours. Muslims are prohibited from eating, drinking, taking medication, and engaging in sexual activities during the fasting period [1]. Nowadays, the non-Muslim community also has a negligible effect from the arising trend of intermittent diet approach in the replacement of traditionally common dietary strategies but the evidence of to which extent this dietary approach might benefit them is remain questionable [2]. The comorbid stress and fear of being infected and the effect of long COVID will affect the quality of life [3]. This is a novel health condition associated with physical or mental deterioration, fatigue, and cold which refers to “post-COVID conditions (PCC)” following COVID-19 infection [4]. Moreover, the consumption of late meals after performing Taraweeh might increase the nocturnal body temperature which leads to delayed bedtime sleep5. Therefore, this study aims to determine the comparison of sleep quality and quality of life among the healthy adult population in the period before Ramadan and during Ramadan and also to find out the possible correlation between these two parameters.&#x0D; &#x0D; This cross-sectional study was conducted on 106 healthy adult populations in Kuala Nerus. The majority (91.5%) of the respondents were aged 19 to 25 years old and 88 (83.0%) of the respondents were female while the rest, 18 (17.0%) were male. Assessment of sleep quality and quality of life was done in two-time intervals before Ramadan (BR) and during Ramadan (DR). Sleep quality; subjective sleep quality, sleep latency, duration of sleep, habitual sleep efficiency, sleep disturbances, sleep medication consumption, and daytime dysfunction were assessed by using PSQI-M, meanwhile, the SF-36 Malay version was used to evaluate the quality of life; physical functioning, role of limitation due to physical health, role of limitation due to emotional problem, energy/fatigue, emotional well-being, social functioning, pain, and general health. All outcomes were measured twice; before Ramadan (one to two weeks prior to Ramadhan month) and during Ramadan (week 2 to 4 of Ramadhan month).&#x0D; &#x0D; There was a significant improvement in overall sleep quality from the global PSQI score during Ramadan as compared to before Ramadan (6.3±2.0 vs 7.5±2.2, p&lt;0.001) followed by sleep latency (min) (0.9±0.6 vs 1.3±0.6, p&lt;0.001), sleep efficiency (%) (0.4±0.6 vs 0.8±0.9, p&lt;0.001) and sleep disturbances (AU) (M=0.8±0.5 vs 1.0±0.5). The rest sleep quality components were not statistically significant. Quality of life in terms of role limitations due to emotional problems during Ramadan is significantly improved than before Ramadan (84.3±24.4 vs 73.9±38.5, p= 0.010). Meanwhile, the other domains were non-statistically significant (Table 1).&#x0D; This study provides evidence on the benefit of practicing Ramadan fasting among a healthy adult population where sleep quality is statistically significantly higher during Ramadan as well as a statistically significant increase in the role limitation due to emotional problems. The greatest correlation is observed between the global PSQI score and pain which indicate the lower the global PSQI score, the absent the feeling of pain and limitation due to pain in the past 4 weeks during Ramadan. A wider population is suggested for future studies to better understand the benefit of Ramadhan Fasting on overall health.

1334-P: Hepatocyte D-ß-Hydroxybutyrate Dehydrogenase Deficiency Improves Glucose Homeostasis and Prevents Diet-Induced Liver Fibrosis

Interest in intermittent fasting, ketogenic diets, and exogenous ketone therapies for prediabetes, diabetes, and nonalcoholic fatty liver disease (NAFLD) is increasing, with numerous studies showing connectivity between ketone body metabolism and NAFLD progression. Previous studies from our group showed that exogenously administered ketone bodies have divergent effects on liver health: acetoacetate (AcAc) ameliorated, while its reduced redox partner D-B-hydroxybutyrate (D-BOHB) exacerbated lobular fibrosis. Here, we study the role of hepatic redox dependent interconversion of AcAc and D-BOHB in the setting of obesity and insulin resistance. Mice deficient in hepatocyte D-BOHB dehydrogenase (BDH1) and their littermate controls were maintained on high fat western diet (WD) for 18 weeks. Post WD challenge, these mice showed similar body weight, glucose, insulin, and circulating lipids in comparison to littermate controls. While livers of hepatocyte-specific BDH1-deficient mice lost the ability to generate D-BOHB, these mice remained capable to interconvert ketone bodies in extrahepatic tissues, leading to substantial circulating D-BOHB. Hepatocyte-specific BDH1 deficient mice maintained on WD displayed diminished glucose production and hepatic oxidative fluxes. Surprisingly, BDH1 deficient mice maintained normal static energy charge and NAD+/NADH ratios. Although insulin signaling in the liver and muscle was comparable between genotypes, knockout mice exhibited improved insulin sensitivity after acute insulin challenge. In addition, livers of knockout mice showed diminished liver fibrosis and oxidative stress. Taken together, these data support the notion for salutary roles of local AcAc, but detrimental roles of local D-BOHB on liver health and suggest that hepatic BDH1-dependent ketone body interconversion is a significant contributor to liver physiology in the setting of obese insulin resistance. Disclosure D.B.Stagg: None. A.R.Seay: None. A.B.Nelson: None. D.A.D’avignon: None. C.C.Hughey: None. P.Puchalska: None. P.A.Crawford: Advisory Panel; Abbott Diabetes, Johnson &amp; Johnson Global Services. Funding NIH DK091538, and NIH AG069781

The effects of a single dose of beta-alanine supplementation on the cardio-respiratory system of well-trained rowing athletes

AbstractPurposeIntensive exercise significantly lowers the pH of muscle and blood; beta-alanine supplementation can increase carnosine levels, the absence of which leads to an early acidosis and fatigue. The aim of our work is to investigate the effect of a single dose of beta-alanine supplementation on well-trained rowing athletes.Materials/MethodsThe spiroergometric parameters of the participants (n = 28) were examined a total of four times (T1,T2,T3,T4). After measurement (T3), participants received a beta-alanine supplementation at a dose of 50 mg/kg−1 body weight. We compared the results of the four measurements as well as the blood lactate values obtained from the fingertip before and after the tests.ResultsThe different load physiological parameters and the lactate values measured after the tests did not show any significant difference. The mean lactate value prior to test (T4) was 1.8 (mmol*L−1), which is significantly higher than the mean-value of the two previous studies: T1 = 1.6 (mmol*L−1); (P = 0.00), T3 = 1.55 (mmol*L−1); (P = 0.04).ConclusionsThe higher lactate value measured before test (T4) was probably due to the longer time to return to the baseline values after the series load. In conclusion, a single dose of beta-alanine supplementation has no effect on performance. In order to elicit the ergogenic effect of beta-alanine, the use of short, intermittent diet therapy intervention is not recommended.

Effect of an Intermittent Meat Protein Diet on Colon Homeostasis

Abstract Objectives The level of dietary protein is a major factor determining gut health. The level of dietary protein is fluctuated in real life, which may affect colon homeostasis. However, it is still less known about it. Here, we investigated how an intermittent protein diet affected inflammatory, gut barrier and microbiota. Methods Six-week-old male C57BL/6J mice received either a casein or pork protein with (i) 20% protein (C), (ii) 5% protein, (iii) 40% protein, or intermittent diet, a diet alternating weekly between 5% protein and 40% protein ((iv) ending on 40% protein or (v) ending on 5% protein)) for up to 16 weeks. The gene expression of inflammatory cytokines, tight junction protein and gut microbiota composition were measured. Results The intermittent intake of casein decreased body weight, but intermittent pork protein diet didn't affect body weight. In casein group, the proinflammatory factors were highly upregulated in intermittent group ending on 5% protein, but the proinflammatory cytokines of intermittent group ending on 40% protein were not significantly affected. However, the two intermittent pork protein groups reduced the expression of proinflammatory cytokines. Additionally, intermittent diet altered gut microbiota composition. Intermittent casein group ending on 40% protein increased richness of gut microbiota, but intermittent pork protein group ending on 5% protein decreased richness and microbial diversity. Conclusions Intermittent diet indeed altered microbiota structure and colon health. In addition to protein level and source, dietary pattern is also an important parameter for host health. Funding Sources This work was funded by Ministry of Science and Technology (10000 Talent Project).

유산소운동, 간헐성금식가 큰 쥐의 식사량과 체중에 미치는 영향

유산소운동, 간헐성금식가 큰 쥐의 식사량과 체중에 미치는 영향

The effect of intermittent diet and/or physical therapy in patients with chronic low back pain: A single-blinded randomized controlled trial

Background and purposeThis study aimed to investigate the effect of intermittent diet and/or physical therapy in patients with chronic low back pain. Materials and methodsSixty sedentary volunteers with chronic low back pain participated in the study. Body weight and body mass index (BMI) were measured. Pain severity was assessed using Visual Analogue Scale (VAS) and Leeds Assessment of Neuropathic Symptoms and Signs (LANSS), while assessment of disability was done using Barthel Index (BI). ResultsThe weight and BMI were reduced after treatment with diet only and diet plus physical therapy (p < 0.001). The pain severity was reduced in all the treated groups (p < 0.001), while BI was increased in the group treated with only physical therapy (p < 0.001). ConclusionThe present study indicated that intermittent diet and/or physical therapy are beneficial to patients with chronic low back pain in terms of pain sensation and daily activities.

Extended Ketogenic Diet Is Necessary For Increases In Protein Acetylation

Decline in mitochondrial function is associated with a decrease in lifespan. We have previously demonstrated that a long-term ketogenic diet (KD) improves mitochondrial function and longevity. However, a life-long KD is difficult to maintain and an intermittent KD might be more viable long term. PURPOSE: Determine how long it takes before a ketogenic diet alters muscle metabolism so that intermittent diets can be developed. METHODS: Four C57BL/6 mice were fed a control diet or 1 or 7 days of continuous KD. At the time of sacrifice, livers, gastrocnemius, brain and kidneys were extracted and frozen in liquid nitrogen before being powdered and homogenized in sucrose lysis buffer and prepared for western blot analysis to determine total acetylated lysine content, total OXPHOS protein, or acetylated p300 content. RESULTS: Following one day of KD, neither acetylated, nor mitochondrial proteins were different than control diet. By seven days of continuous KD diet, total acetylated proteins increased in the liver, kidney and gastrocnemius muscle. Specifically, acetylation of p300 was 3.4±0.89-fold greater following 7 days of KD. Unlike the other tissues the brain showed no difference in acetylated proteins by 7 days. An increase in mitochondrial mass was only seen in the liver at 7 days of KD. CONCLUSIONS: A short term ketogenic diet can be used to rapidly alter protein acetylation in the liver, kidney and muscle. These data suggest that an intermittent keto diet may be useful in promoting a biochemical change in muscle that promotes mitochondrial function and may benefit long-term muscle function.

1957-P: Intermittent Ketogenic Diet Ameliorates Diet-Induced Obesity and Fatty Liver with Improved FGF21 Signaling

Recently, ketogenic diet has been found to be effective on improving obesity. Fibroblast growth factor 21 (FGF-21) is an endocrine factor mainly synthesized in the liver and shown to impact the metabolism of multiple tissues. Here, we investigated the effect of intermittent ketogenic diet on obesity and the sensitivity of FGF-21. Eight-week-old C57BL/6 mice were subjected to a chow diet (CD group), a high fat diet (HFD group), an intermittent chow diet (iCD group) or an intermittent ketogenic diet (iKD group) for 16 weeks. The intermittent diet intervention began with an HFD and was alternated with a chow diet or a ketogenic diet biweekly. Although the average energy intake of iKD group was highest in the four groups, the body weight, fasting blood glucose, the body fat mass and the weight of liver, epididymal adipose tissues (eWAT), subcutaneous adipose tissue (sWAT) and brown adipose tissue (BAT) of iKD group were ameliorated remarkably when compared to HFD group. The insulin sensitivity of iKD group was greatly improved as well. Both the histological results and the quantification of liver triglyceride showed that hepatic steatosis was significantly alleviated in iKD group. Western blotting showed that lipid metabolism in liver was greatly improved by iKD. What’s more, the cold exposure test showed that the iKD group had the best cold tolerance in the four groups. The mRNA expression of FGF-21 was greatly upregulated and hepatic inflammation was ameliorated in livers of iKD group. HE staining showed that the adipocytes in eWAT and sWAT were smaller in iKD group. The whitening of BAT was also improved in iKD group. Both mRNA and protein levels of UCP1 and PGC1α were remarkably upregulated by iKD in eWAT, sWAT and BAT. The mRNA levels of FGFR1 and KLB, which are related to FGF-21 sensitivity, were observed to be improved in eWAT and sWAT. Our data demonstrated that iKD ameliorates diet-induced obesity and fatty liver, and improved insulin sensitivity and cold tolerance with improved FGF-21 signaling. Disclosure W. Guo: None. W. Wang: None. W. Li: None.

Intermittent cafeteria diet identifies fecal microbiome changes as a predictor of spatial recognition memory impairment in female rats

Excessive consumption of diets high in saturated fat and sugar impairs short-term spatial recognition memory in both humans and rodents. Several studies have identified associations between the observed behavioral phenotype and diet-induced changes in adiposity, hippocampal gene expression of inflammatory and blood–brain barrier-related markers, and gut microbiome composition. However, the causal role of such variables in producing cognitive impairments remains unclear. As intermittent cafeteria diet access produces an intermediate phenotype, we contrasted continuous and intermittent diet access to identify specific changes in hippocampal gene expression and microbial species that underlie the cognitive impairment observed in rats fed continuous cafeteria diet. Female adult rats were fed either regular chow, continuous cafeteria diet, or intermittent cafeteria diet cycles (4 days regular chow and 3 days cafeteria) for 7 weeks (12 rats per group). Any cafeteria diet exposure affected metabolic health, hippocampal gene expression, and gut microbiota, but only continuous access impaired short-term spatial recognition memory. Multiple regression identified an operational taxonomic unit, from species Muribaculum intestinale, as a significant predictor of performance in the novel place recognition task. Thus, contrasting intermittent and continuous cafeteria diet exposure allowed us to identify specific changes in microbial species abundance and growth as potential underlying mechanisms relevant to diet-induced cognitive impairment.

2019-P: Deletion of Hepatic SIRT1 Enhances the Effect of Ketogenic Diets on Ameliorating Obesity and Metabolic Disorders

A ketogenic diet, one kind of carbohydrate-restricted diets, is considered to reduce body weight and improve metabolic disorders. However, the mechanism of how a ketogenic diet provides such metabolic benefits is unclear. SIRT1, a NAD-dependent deacetylase, plays an important role in lipid metabolism. We investigated the role of hepatic SIRT1 in the beneficial effect of ketogenic diets on improving obesity and metabolic disorder. In this study, eight-week-old male liver-specific SIRT1 deletion (SIRT1 LKO) mice and control mice were subjected to a high fat diet (HFD) or an intermittent ketogenic diet (iKD), ketogenic diet alternated biweekly with HFD, for 12 weeks. The results showed that the body weight of mice fed on iKD was significantly lower than mice fed on HFD, even though higher energy intake was observed when mice were fed on a ketogenic diet. Interestingly, SIRT1 LKO mice on HFD were slightly heavier than control mice on HFD, but SIRT1 LKO mice on iKD were thinner than control mice on iKD. Lower fasting blood glucose was observed after every 2-week ketogenic diets intervention, and there was no significant difference between SIRT1 LKO mice and control mice. Compared to HFD, iKD significantly improved insulin resistance. Notably, iKD improved the glucose metabolism of SIRT1 LKO mice, but such improvement was not observed in control mice. These results indicate that an intermittent ketogenic diet improves metabolic disorders induced by HFD and has further beneficial effect on obesity and metabolic disorder in the absent of hepatic SIRT1. The underlying mechanism will be further studied. Disclosure W. Guo: None. F. Xu: None. G. Li: None. H. Liang: None. M. Cai: None.

Intermittent Dieting: Theoretical Considerations for the Athlete

Athletes utilise numerous strategies to reduce body weight or body fat prior to competition. The traditional approach requires continuous energy restriction (CER) for the entire weight loss phase (typically days to weeks). However, there is some suggestion that intermittent energy restriction (IER), which involves alternating periods of energy restriction with periods of greater energy intake (referred to as ‘refeeds’ or ‘diet breaks’) may result in superior weight loss outcomes than CER. This may be due to refeed periods causing transitory restoration of energy balance. Some studies indicate that intermittent periods of energy balance during energy restriction attenuate some of the adaptive responses that resist the continuation of weight and fat loss. While IER—like CER—is known to effectively reduce body fat in non-athletes, evidence for effectiveness of IER in athletic populations is lacking. This review provides theoretical considerations for successful body composition adjustment using IER, with discussion of how the limited existing evidence can be cautiously applied in athlete practice.

Rationale for novel intermittent dieting strategies to attenuate adaptive responses to energy restriction.

Eating patterns involving intermittent energy restriction (IER) include 'intermittent fasting' where energy intake is severely restricted for several 'fasting' days per week, with 'refeeding' days (involving greater energy intake than during fasting days) at other times. Intermittent fasting does not improve weight loss compared to continuous energy restriction (CER), where energy intake is restricted every day. We hypothesize that weight loss from IER could be improved if refeeding phases involved restoration of energy balance (i.e. not ongoing energy restriction, as during intermittent fasting). There is some evidence in adults with overweight or obesity showing that maintenance of a lower weight may attenuate (completely or partially) some of the adaptive responses to energy restriction that oppose ongoing weight loss. Other studies show some adaptive responses persist unabated for years after weight loss. Only five randomized controlled trials in adults with overweight or obesity have compared CER with IER interventions that achieved energy balance (or absence of energy restriction) during refeeding phases. Two reported greater weight loss than CER, whereas three reported similar weight loss between interventions. While inconclusive, it is possible that achieving energy balance (i.e. avoiding energy restriction or energy excess) during refeeding phases may be important in realizing the potential of IER.