Perspective: Time-Restricted Eating Compared with Caloric Restriction: Potential Facilitators and Barriers of Long-Term Weight Loss Maintenance

Time-Restricted Eating in Community-Dwelling Adults: Correlates of Adherence and Discontinuation in a Cross-Sectional Online Survey Study

BACKGROUND

Time-restricted eating (TRE), a type of intermittent fasting in which all daily calories are consumed within a window of ≤12 hours, is hypothesized to promote long-term weight management because of its relative simplicity.

OBJECTIVE

This study reports correlates of adherence among community-dwelling adults currently or formerly following a TRE dietary strategy.

DESIGN

A 25-minute cross-sectional online survey was developed, including questions about TRE perceptions, behaviors, motivators and drivers, and demographics. The survey was administered in February 2021 via Prolific, an online platform for sample recruitment and survey dissemination.

PARTICIPANTS

Eligibility criteria included US adult ages 18+ who currently or formerly (past 3 months) followed TRE (ie, consumed all daily calories within a window of ≤12 hours) for a minimum of 1 week.

STATISTICAL ANALYSES

χ2 tests and analysis of covariance (ANCOVA; adjusting for sex and age) compared responses between current and former followers.

RESULTS

Current followers (n = 296, mean [SD]: 34.2 ± 12.2y) were older than former followers (n = 295, mean [SD]: 31.1 ± 10.9 y) and practiced TRE for longer (median: 395 vs 90 days, P < 0.001). Current followers reported more success with meeting TRE goals (P ≤ 0.015), were less likely to report TRE concerns (P < 0.001), and more likely to report TRE satisfaction (P < 0.001). Four TRE motivators were more important among current (vs former) followers: weight maintenance, health (not weight), improved sleep, and preventing disease (P ≤ 0.017); weight loss was more important among former (vs current) followers (P = 0.003). Among adherence drivers, ability to work from home and the impact of COVID-19 were reported as more helpful for TRE adherence among current compared with former followers (P ≤ 0.028).

CONCLUSIONS

TRE motivators and drivers differed between current and former followers; interventions tailored to individuals' preferences and circumstances may benefit TRE adherence.

Intermittent Fasting: Myths, Fakes and Truth on This Dietary Regimen Approach

Intermittent fasting (IF) has been indicated as a valuable alternative to the classical caloric restriction dietary regimen for lowering body weight and preventing obesity-related complications, such as metabolic syndrome and type II diabetes. However, is it effective? In this review article, we analyzed over 50 clinical studies in which IF, conducted by alternate day fasting (ADF) or time-restricted feeding (TRF), was compared with the caloric restriction approach. We evaluated the different roles of IF in treating and preventing human disorders such as metabolic syndrome, type II diabetes, and some types of cancer, as well as the usefulness of IF in reducing body weight and cardiovascular risk factors such as hypertension. Furthermore, we explored the cellular pathways targeted by IF to exert their beneficial effects by activating effector proteins that modulate cell functions and resistance to oxidative stress. In contrast, we investigated concerns regarding human health related to the adoption of IF dietary regimens, highlighting the profound debate surrounding weight loss regimens. We examined and compared several clinical trials to formulate an updated concept regarding IF and its therapeutic potential.

The Effect of Time-Restricted Eating Combined with Exercise on Body Composition and Metabolic Health: A Systematic Review and Meta-Analysis

BACKGROUND

Time-restricted eating (TRE) is increasingly popular, but its benefits in combination with exercise still need to be determined.

OBJECTIVES

This systematic review and meta-analysis aimed to evaluate the efficacy of TRE combined with exercise compared with control diet with exercise in improving the body composition and metabolic health of adults.

METHODS

Five electronic databases were searched for relevant studies. Randomized controlled trials (RCTs) examining the effect of TRE combined with exercise on body composition and metabolic health in adults were included. All results in the meta-analysis are reported as mean difference (MD) with 95% confidence interval (CI). Study quality was assessed using the revised Cochrane Risk of Bias Tool and Grading of Recommendations Assessment, Development, and Evaluation assessment.

RESULTS

In total, 19 RCTs comprising 568 participants were included in this systematic review and meta-analysis. TRE combined with exercise likely reduced the participants' body mass (MD: -1.86 kg; 95% CI: -2.75, -0.97 kg) and fat mass (MD: -1.52 kg; 95% CI: -2.07, -0.97 kg) when compared with the control diet with exercise. In terms of metabolic health, the TRE combined with exercise group likely reduced triglycerides (MD: -13.38 mg/dL, 95% CI: -21.22, -5.54 mg/dL) and may result in a reduction in low-density lipoprotein (MD: -8.52 mg/dL; 95% CI: -11.72, -5.33 mg/dL) and a large reduction in leptin (MD: -0.67 ng/mL; 95% CI: -1.02, -0.33 ng/mL). However, TRE plus exercise exhibited no additional benefit on the glucose profile, including fasting glucose and insulin, and other lipid profiles, including total cholesterol and high-density lipoprotein concentrations, compared with the control group.

CONCLUSIONS

Combining TRE with exercise may be more effective in reducing body weight and fat mass and improving lipid profile than control diet with exercise. Implementing this approach may benefit individuals aiming to achieve weight loss and enhance their metabolic well-being. This study was registered in PROSPERO as CRD42022353834.

It's About Timing: Contrasting the Metabolic Effects of Early vs. Late Time-Restricted Eating in Humans

PURPOSE OF REVIEW

Time-restricted eating (TRE), a form of intermittent fasting, restricts feeding time across the day, imposing a daily 'eating window'. The time of day when the eating window occurs could result in differential metabolic effects. Here, we describe recent intervention studies in humans assessing the metabolic consequences of an early- (i.e., eating window starting in the early morning) vs. late (i.e., eating window starting after midday)-TRE protocol.

RECENT FINDINGS

Well-controlled studies indicate that both TRE protocols effectively reduce body weight and improve altered glucose metabolism, lipid profile, inflammation, or blood pressure levels. An early-TRE (e-TRE) might have a further positive impact on improving blood glucose, insulin levels, and insulin resistance. However, the studies directly assessing the metabolic consequences of an early- vs. late-TRE have shown dissimilar findings, and more well-controlled clinical trials are needed on the metabolic benefits of these two types of TRE. Evidence suggests that an e-TRE might have enhanced metabolic results, particularly regarding glucose homeostasis. More long-term studies, including larger sample sizes, are needed to assess the metabolic, circadian, and adherence benefits, together with socio-cultural acceptance of both TRE approaches.

Effects of 3 months of 10-h per-day time-restricted eating and 3 months of follow-up on bodyweight and cardiometabolic health in Danish individuals at high risk of type 2 diabetes: the RESET single-centre, parallel, superiority, open-label, randomised controlled trial

BACKGROUND

Time-restricted eating (TRE) has been suggested to be a simple, feasible, and effective dietary strategy for individuals with overweight or obesity. We aimed to investigate the effects of 3 months of 10-h per-day TRE and 3 months of follow-up on bodyweight and cardiometabolic risk factors in individuals at high risk of type 2 diabetes.

METHODS

This was a single-centre, parallel, superiority, open-label randomised controlled clinical trial conducted at Steno Diabetes Center Copenhagen (Denmark). The inclusion criteria were age 30-70 years with either overweight (ie, BMI ≥25 kg/m2) and concomitant prediabetes (ie, glycated haemoglobin [HbA1c] 39-47 mmol/mol) or obesity (ie, BMI ≥30 kg/m2) with or without prediabetes and a habitual self-reported eating window (eating and drinking [except for water]) of 12 h per day or more every day and of 14 h per day or more at least 1 day per week. Individuals were randomly assigned 1:1 to 3 months of habitual living (hereafter referred to as the control group) or TRE, which was a self-selected 10-h per-day eating window placed between 0600 h and 2000 h. Randomisation was done in blocks varying in size and was open for participants and research staff, but outcome assessors were masked during statistical analyses. The randomisation list was generated by an external statistician. The primary outcome was change in bodyweight, assessed after 3 months (12 weeks) of the intervention and after 3 months (13 weeks) of follow-up. Adverse events were reported and registered at study visits or if participants contacted study staff to report events between visits. This trial is registered on ClinicalTrials.gov (NCT03854656).

FINDINGS

Between March 12, 2019, and March 2, 2022, 100 participants (66 [66%] were female and 34 [34%] were male; median age 59 years [IQR 52-65]) were enrolled and randomly assigned (50 to each group). Of those 100, 46 (92%) in the TRE group and 46 (92%) in the control group completed the intervention period. After 3 months of the intervention, there was no difference in bodyweight between the TRE group and the control group (-0·8 kg, 95% CI -1·7 to 0·2; p=0·099). Being in the TRE group was not associated with a lower bodyweight compared with the control group after subsequent 3-month follow-up (-0·2 kg, -1·6 to 1·2). In the per-protocol analysis, participants who completed the intervention in the TRE group lost 1·0 kg (-1·9 to -0·0; p=0·040) bodyweight compared with the control group after 3 months of intervention, which was not maintained after the 3-month follow-up period (-0·4 kg, -1·8 to 1·0). During the trial and follow-up period, one participant in the TRE group reported a severe adverse event: development of a subcutaneous nodule and pain when the arm was in use. This side-effect was evaluated to be related to the trial procedures.

INTERPRETATION

3 months of 10-h per-day TRE did not lead to clinically relevant effects on bodyweight in middle-aged to older individuals at high risk of type 2 diabetes.

FUNDING

Novo Nordisk Foundation, Aalborg University, Helsefonden, and Innovation Fund Denmark.

Unlocking the power of synergy: High-intensity functional training and early time-restricted eating for transformative changes in body composition and cardiometabolic health in inactive women with obesity

OBJECTIVE

The purpose of this study was to examine the long-term effects of time-restricted eating (TRE), with or without high intensity functional training (HIFT), on body composition and cardiometabolic biomarkers among inactive women with obesity.

METHODS

Sixty-four women (BMI = 35.03 ± 3.8 kg/m2; age = 32.1 ± 10 years) were randomly allocated to either: (1) TRE (≤8-h daily eating window, with ad libitum energy intake) group; (2) HIFT (3 sessions/week) group; or (3) TRE combined with HIFT (TRE-HIFT) group. The interventions lasted 12 weeks with a pre-post measurement design. A HIFT session consists of 8 sets of multiple functional exercises with self-selected intensity (20 or 30s work/10s rest).

RESULTS

TRE-HIFT showed a greater decrease of waist and hip circumferences and fat mass compared to TRE (p = 0.02, p = 0.02 and p<0.01; respectively) and HIFT (p = 0.012, p = 0.028 and p<0.001; respectively). Weight and BMI decreased in TRE-HIFT compared to HIFT group (p<0.001; for both). Fat-free mass was lower in TRE compared to both HIFT and TRE-HIFT groups (p<0.01 and p<0.001; respectively). Total cholesterol, triglyceride, insulin, and HOMA-IR decreased in TRE-HIFT compared to both TRE (p<0.001, p<0.01, p = 0.015 and p<0.01; respectively) and HIFT (p<0.001, p = 0.02, p<0.01 and p<0.001; respectively) groups. Glucose level decreased in TRE-HIFT compared to HIFT (p<0.01). Systolic blood pressure decreased significantly in both TRE-HIFT and HIFT groups compared to TRE group (p = 0.04 and p = 0.02; respectively).

CONCLUSION

In inactive women with obesity, combining TRE with HIFT can be a good strategy to induce superior effects on body composition, lipid profile and glucose regulation compared with either diet or exercise intervention alone.

TRIAL REGISTRATION

Clinical Trials Number: PACTR202301674821174.

Does time-restricted eating add benefits to calorie restriction? A systematic review

OBJECTIVE

A growing body of evidence has supported the health benefits of extended daily fasting, known as time-restricted eating (TRE); however, whether the addition of TRE enhances the known benefits of calorie restriction (CR) remains unclear.

METHODS

PubMed, Scopus, the Cochrane Library, and Google Scholar were searched through April 2023. This systematic review includes randomized controlled trials (RCTs) that compared CR + TRE with CR alone in energy-matched conditions of at least 8 weeks in duration that assessed changes in body weight and cardiometabolic disease risk factors in adults with overweight and/or obesity.

RESULTS

Seven studies were identified (n = 579). Two studies reported greater weight loss and reductions in diastolic blood pressure with CR + TRE compared with CR alone after 8 to 14 weeks, whereas one study reported greater improvements in triglycerides and glucose tolerance with CR + TRE (3 days/week) compared with CR alone following 26 weeks. One study reported significant increases in homeostatic model assessment of insulin resistance (HOMA-IR) levels with CR + TRE versus CR alone after 8 weeks. There were no statistically significant differences in any other outcome variable between the two interventions.

CONCLUSIONS

The addition of TRE to CR regimens resulted in greater weight loss and improvements in cardiometabolic risk factors in some studies; however, the majority of studies did not find additional benefits.

Hypercaloric low-carbohydrate high-fat diet protects against the development of nonalcoholic fatty liver disease in obese mice in contrast to isocaloric Western diet

Objective

Obesity and metabolic complications, such as type 2 diabetes and nonalcoholic fatty liver disease (NAFLD), are one of the greatest public health challenges of the 21st century. The major role of high sugar and carbohydrate consumption rather than caloric intake in obesity and NAFLD pathophysiology remains a subject of debate. A low-carbohydrate but high-fat diet (LCHFD) has shown promising results in obesity management, but its effects in preventing NAFLD need to be detailed. This study aims to compare the effects of a LCHFD with a high-fat high-sugar obesogenic Western diet (WD) on the progression of obesity, type 2 diabetes, and nonalcoholic fatty liver disease.

Methods

Male C57BL/6J mice were initially fed a WD for 10 weeks. Subsequently, they were either switched to a LCHFD or maintained on the WD for an additional 6 weeks. Hepatic effects of the diet were explored by histological staining and RT-qPCR.

Results

After the initial 10 weeks WD feeding, LCHF diet demonstrated effectiveness in halting weight gain, maintaining a normal glucose tolerance and insulin levels, in comparison to the WD-fed mice, which developed obesity, glucose intolerance, increased insulin levels and induced NAFLD. In the liver, LCHFD mitigated the accumulation of hepatic triglycerides and the increase in Fasn relative gene expression compared to the WD mice. Beneficial effects of the LCHFD occurred despite a similar calorie intake compared to the WD mice.

Conclusion

Our results emphasize the negative impact of a high sugar/carbohydrate and lipid association for obesity progression and NAFLD development. LCHFD has shown beneficial effects for NAFLD management, notably improving weight management, and maintaining a normal glucose tolerance and liver health.

Conceptualization and Assessment of 24-H Timing of Eating and Energy Intake: A Methodological Systematic Review of the Chronic Disease Literature

Timing of eating (TOE) and energy intake (TOEI) has important implications for chronic disease risk beyond diet quality. The 2020 Dietary Guidelines Advisory Committee recommended developing consistent terminology to address the lack of TOE/TOEI standardization. The primary objective of this methodological systematic review was to characterize the conceptualization and assessment of TOE/TOEI within the chronic disease literature (International Prospective Register of Systematic Reviews registration number: CRD42021236621). Literature searches in Cumulative Index to Nursing and Allied Health Literature (CINAHL) Plus, Embase, PubMed, and Scopus were limited to English language publications from 2000 to August 2022. Eligible studies reported the association between TOE/TOEI and obesity, cardiovascular disease, type 2 diabetes mellitus, cancer, or a related clinical risk factor among adults (≥19 y) in observational and intervention studies. A qualitative synthesis described and compared TOE/TOEI conceptualization, definitions, and assessment methods across studies. Of the 7579 unique publications identified, 259 studies (observational [51.4 %], intervention [47.5 %], or both [1.2 %]) were eligible for inclusion. Key findings indicated that most studies (49.6 %) were conducted in the context of obesity and body weight. TOE/TOEI variables or assigned conditions conceptualized interrelated aspects of time and eating or energy intake in varying ways. Common TOE/TOEI conceptualizations included the following: 1) timepoint (specific time to represent when intake occurs, such as time of breakfast [74.8 %]); 2) duration (length of time or interval when intake does/does not occur, such as "eating window" [56.5 %]); 3) distribution (proportion of daily intake at a given time interval, such as "percentage of energy before noon" [29.8 %]); and 4) cluster (grouping individuals based on temporal ingestive characteristics [5.0 %]). Assessment, definition, and operationalization of 24-h TOE/TOEI variables varied widely across studies. Observational studies most often used surveys or questionnaires (28.9 %), whereas interventions used virtual or in-person meetings (23.8 %) to assess TOE/TOEI adherence. Overall, the diversity of terminology and methods solidifies the need for standardization to guide future research in chrononutrition and to facilitate inter-study comparisons.

Development of Momentary Appetite Capture (MAC): A versatile tool for monitoring appetite over long periods

Understanding how an intervention impacts appetite in real-life settings and over several days remains a challenging and under-explored research question. To this end, we developed Momentary Appetite Capture (MAC), a form of ecological momentary assessment that combines automated text messaging with an online platform. Participants report their appetite using visual analogue scales (hunger, desire to eat, and fullness) and a virtual portion-size selection task. In two separate studies, we assessed the feasibility and test-retest reliability of MAC. Participants were prompted every 2 hours over a 14-hour window, and they repeated this assessment over two consecutive weekdays. For each participant, we calculated a daily time-averaged area under the curve (AUC) for each appetite measure. In Study One (N = 25) time-averaged AUC was significantly positively correlated across test days for hunger (r = 0.563, p = .003), desire to eat (r = 0.515, p = .008) and prospective portion size (r = 0.914, p < .001), but not for fullness (r = 0.342, p = .094). Participants completed 95% of MACs (380 of 400), and we used participant feedback to improve the MAC tool and study protocol for Study Two. In Study Two (N = 31), 94% of MACs were completed (468 of 496). Across days, time-averaged AUC was significantly positively correlated for hunger (r = 0.595, p = < .001), fullness (r = 0.501, p = .004), desire to eat (r = 0.585, p < .001), and prospective portion size (r = 0.757, p < .001). Together, these studies suggest that MAC could be an acceptable and reliable tool to track appetite throughout the day. In the future, MAC could be used to explore the impact of weight-loss interventions on natural fluctuations in appetite.

Time-restricted eating improves health because of energy deficit and circadian rhythm: A systematic review and meta-analysis

Time-restricted eating (TRE) is an effective way to lose weight and improve metabolic health in animals. Yet whether and how these benefits apply to humans is unclear. This systematic review and meta-analysis examined the effect of TRE in people with overweight and obesity statuses. The results showed that TRE led to modest weight loss, lower waist circumference and energy deficits. TRE also improved body mass index, fat mass, lean body mass, systolic blood pressure, fasting glucose levels, fasting insulin levels, and HbA1c%. Subgroup analysis demonstrated more health improvements in the TRE group than the control group under the ad libitum intake condition than in the energy-prescribed condition. Eating time-of-day advantages were only seen when there was considerable energy reduction in the TRE group than the control group (ad libitum condition), implying that the benefits of TRE were primarily due to energy deficit, followed by alignment with eating time of day.

Home-based exercise interventions' impact on breast cancer survivors' functional performance: a systematic review

INTRODUCTION

Home-based exercise (HBE) programs can be a feasible strategy to enhance functional performance and promote physical activity (PA) in breast cancer survivors. A deeper analysis of the effects of HBE interventions, structured by HBE program type and treatment phase, is needed. This systematic review aimed to synthesize the evidence on HBE interventions' impact on breast cancer survivors' functional performance, PA levels, and program adherence rates, according to HBE intervention type and treatment phase.

METHODS

A comprehensive search of peer-reviewed articles reporting HBE interventions' effects on the outcomes of interest was performed in Pubmed, Google Scholar, EBSCO, Web of Science, Science Direct, and B-ON until January 15th, 2024. Data were synthesized according to Denton's domains to classify HBE interventions (prescription: structured vs. unstructured; Delivery method: supervised vs. facilitated vs. unsupervised) and treatment phase. Methodological quality appraisal was performed using the Effective Public Health Practice Project tool.

RESULTS

Twenty-six studies were included. Most studies conducted structured/facilitated interventions and reported positive effects on functional performance (particularly aerobic capacity), increases in PA levels, and high adherence rates (> 70%) during and post-treatment.

CONCLUSION

HBE interventions may be feasible to improve functional performance and promote physical activity among breast cancer survivors. Further studies are needed to confirm which HBE intervention type is more appropriate for each treatment phase. More evidence applying HBE interventions with different designs is required to allow the drawing of more solid conclusions. Studies exploring the effects of HBE interventions on the pre-treatment phase are needed.

Intermittent fasting-the future treatment in NASH patients?

NASH is one of the leading causes of chronic liver disease with the potential of evolving towards end-stage liver disease and HCC, even in the absence of cirrhosis. Apart from becoming an increasingly prevalent indication for liver transplantation in cirrhotic and HCC patients, its burden on the healthcare system is also exerted by the increased number of noncirrhotic NASH patients. Intermittent fasting has recently gained more interest in the scientific community as a possible treatment approach for different components of metabolic syndrome. Basic science and clinical studies have shown that apart from inducing body weight loss, improving cardiometabolic parameters, namely blood pressure, cholesterol, and triglyceride levels; insulin and glucose metabolism; intermittent fasting can reduce inflammatory markers, endoplasmic reticulum stress, oxidative stress, autophagy, and endothelial dysfunction, as well as modulate gut microbiota. This review aims to further explore the main NASH pathogenetic metabolic drivers on which intermittent fasting can act upon and improve the prognosis of the disease, and summarize the current clinical evidence.

Timing Matters: The Interplay between Early Mealtime, Circadian Rhythms, Gene Expression, Circadian Hormones, and Metabolism-A Narrative Review

Achieving synchronization between the central and peripheral body clocks is essential for ensuring optimal metabolic function. Meal timing is an emerging field of research that investigates the influence of eating patterns on our circadian rhythm, metabolism, and overall health. This narrative review examines the relationship between meal timing, circadian rhythm, clock genes, circadian hormones, and metabolic function. It analyzes the existing literature and experimental data to explore the connection between mealtime, circadian rhythms, and metabolic processes. The available evidence highlights the importance of aligning mealtime with the body's natural rhythms to promote metabolic health and prevent metabolic disorders. Specifically, studies show that consuming meals later in the day is associated with an elevated prevalence of metabolic disorders, while early time-restricted eating, such as having an early breakfast and an earlier dinner, improves levels of glucose in the blood and substrate oxidation. Circadian hormones, including cortisol and melatonin, interact with mealtimes and play vital roles in regulating metabolic processes. Cortisol, aligned with dawn in diurnal mammals, activates energy reserves, stimulates appetite, influences clock gene expression, and synchronizes peripheral clocks. Consuming meals during periods of elevated melatonin levels, specifically during the circadian night, has been correlated with potential implications for glucose tolerance. Understanding the mechanisms of central and peripheral clock synchronization, including genetics, interactions with chronotype, sleep duration, and hormonal changes, provides valuable insights for optimizing dietary strategies and timing. This knowledge contributes to improved overall health and well-being by aligning mealtime with the body's natural circadian rhythm.

General Practitioners' Knowledge, Attitudes, and Practices of Dietary Advice for Weight Control in Their Overweight Patients: A Scoping Review

This scoping review assessed the knowledge, attitudes, and practices of general practitioners (GPs) regarding dietary advice for weight management. A systematic search of PubMed, EMBASE, CINAHL, and MEDLINE was conducted for any qualitative, quantitative, and mixed-methods studies published in the past five years that informed GPs' dietary advice for weight control. Thirteen studies were included in the analysis after screening 881 papers. These studies tended to focus mostly on GPs' practices rather than their knowledge and attitudes. The most frequently mentioned dietary advice was to reduce calorie intake; however, 32 different types of dietary advice were identified in the literature, including approaches such as intermittent fasting and a ketogenic diet that are not recommended in current guidelines. GPs showed varying levels of knowledge and attitudes regarding the best dietary advice for patients. Further research is needed to better understand GP perspectives, with efforts to assist GPs in providing tailored advice based on the latest evidence to improve patient outcomes required.

The Effect of Intermittent Fasting on Appetite: A Systematic Review and Meta-Analysis

Previously, narrative reviews have considered the effects of intermittent fasting on appetite. One suggestion is that intermittent fasting attenuates an increase in appetite that typically accompanies weight loss. Here, we conducted the first systematic review and meta-analysis to quantify the effects of intermittent fasting on appetite, when compared to a continuous energy restriction intervention. Five electronic databases and trial registers were searched in February 2021 and February 2022. Abstracts (N = 2800) were screened and 17 randomized controlled trials (RCTs), consisting of a variety of intermittent fasting regimes, met our inclusion criteria. The total number of participants allocated to interventions was 1111 and all RCTs were judged as having either some concerns or a high risk of bias (Cochrane RoB 2.0 tool). Random effects meta-analyses were conducted on change-from-baseline appetite ratings. There was no clear evidence that intermittent fasting affected hunger (WMD = -3.03; 95% CI [-8.13, 2.08]; p = 0.25; N = 13), fullness (WMD = 3.11; 95% CI [-1.46, 7.69]; p = 0.18; N = 10), desire to eat (WMD = -3.89; 95% CI [-12.62, 4.83]; p = 0.38; N = 6), or prospective food consumption (WMD = -2.82; 95% CI [-3.87, 9.03]; p = 0.43; N = 5), differently to continuous energy restriction interventions. Our results suggest that intermittent fasting does not mitigate an increase in our drive to eat that is often associated with continuous energy restriction.

To Eat or Not to Eat-A Qualitative Exploration and Typology of Restrictive Dietary Practices among Middle-Aged and Older Adults

Favorable diets often include restrictive practices that have proven health benefits, even if initiated later in life. The aim of this qualitative study is to gain a comprehensive understanding of Restrictive Dietary Practices (RDPs) among a sample of middle-aged and older German adults (aged 59-78 years). We conducted 24 narrative in-depth interviews and analyzed the data using qualitative content analysis (Kuckartz). Following an inductive thematic approach, a typology was reconstructed comprising four typical RDP characteristics: I. The Holistically Restraining Type, II. The Dissonant-savoring Restraining Type, III. The Reactively Restraining Type, and IV. The Unintentionally Restraining Type. These types differed regarding the practical implementation of, e.g., restrictive food choice into everyday routines, barriers to do so, as well as with respect to attitudes and motives underlying RDPs. The major motives for adopting a RDP involved health, well-being, ethical, and ecological concerns. The most prominent barriers to a 'successful' adoption of RDPs were the enjoyment of food and the desire for spontaneity and freedom of (food) choice. Our study offers an in-depth understanding of the aspects that shape the widespread practice of dietary restriction among middle-aged and older adults. Lifeworld-related changes in RDPs and possible 'type shiftings' are discussed as well as the meaning and chances of RDPs for public health promotion.

Time restricted eating facilitates weight loss and improves cardiometabolic profile in a female veteran with multiple sclerosis: A case report

Context: To counteract cumulative weight gain, a female veteran with multiple sclerosis with spinal cord involvement initiated a program of time restricted eating (TRE), eating all calories within a daily 6-hour window.Findings: The patient experienced significant weight loss and improved cardiometabolic markers.Conclusion/Clinical Relevance: Additional research is warranted to study TRE to mitigate obesity.

Turning Back the Clock: A Retrospective Single-Blind Study on Brain Age Change in Response to Nutraceuticals Supplementation vs. Lifestyle Modifications

BACKGROUND

There is a growing consensus that chronological age (CA) is not an accurate indicator of the aging process and that biological age (BA) instead is a better measure of an individual's risk of age-related outcomes and a more accurate predictor of mortality than actual CA. In this context, BA measures the "true" age, which is an integrated result of an individual's level of damage accumulation across all levels of biological organization, along with preserved resources. The BA is plastic and depends upon epigenetics. Brain state is an important factor contributing to health- and lifespan.

METHODS AND OBJECTIVE

Quantitative electroencephalography (qEEG)-derived brain BA (BBA) is a suitable and promising measure of brain aging. In the present study, we aimed to show that BBA can be decelerated or even reversed in humans (N = 89) by using customized programs of nutraceutical compounds or lifestyle changes (mean duration = 13 months).

RESULTS

We observed that BBA was younger than CA in both groups at the end of the intervention. Furthermore, the BBA of the participants in the nutraceuticals group was 2.83 years younger at the endpoint of the intervention compared with their BBA score at the beginning of the intervention, while the BBA of the participants in the lifestyle group was only 0.02 years younger at the end of the intervention. These results were accompanied by improvements in mental-physical health comorbidities in both groups. The pre-intervention BBA score and the sex of the participants were considered confounding factors and analyzed separately.

CONCLUSIONS

Overall, the obtained results support the feasibility of the goal of this study and also provide the first robust evidence that halting and reversal of brain aging are possible in humans within a reasonable (practical) timeframe of approximately one year.

Beneficial effects of time and energy restriction diets on the development of experimental acute kidney injury in Rat: Bax/Bcl-2 and histopathological evaluation

People's lifestyles and, especially, their eating habits affect their health and the functioning of the organs in their bodies, including the kidneys. One's diet influences the cells' responses to stressful conditions such as acute kidney injury (AKI). This study aims to determine the preconditioning effects of four different diets: energy restriction (ER) diet, time restriction (TR) eating, intermittent fasting (IF), and high-fat diet (HF) on histopathological indices of the kidney as well as the molecules involved in apoptosis during AKI. Adult male rats underwent ER, TR, IF, and HF diets for eight weeks. Then, AKI was induced, and renal function indices, histopathological indices, and molecules involved in apoptosis were measured. In animals with AKI, urinary albumin excretion, serum urea, creatinine and, Bax/Bcl-2 ratio increased in the kidney, while renal eGFR decreased. ER and TR diets improved renal parameters and prevented an increase in the Bax/Bcl-2 ratio. The IF diet improved renal parameters but had no effect on the Bax/Bcl-2 ratio. On the other hand, the HF diet worsened renal function and increased the Bax/Bcl-2 ratio. Histopathological examination also showed improved kidney conditions in the ER and TR groups and more damage in the HF group. This study demonstrated that ER and TR diets have renoprotective effects on AKI and possibly cause the resistance of kidney cells to damage by reducing the Bax/Bcl-2 ratio and improving apoptotic conditions.

When should I eat: A circadian view on food intake and metabolic regulation

The circadian clock is a hierarchical timing system regulating most physiological and behavioral functions with a period of approximately 24 h in humans and other mammalian species. The circadian clock drives daily eating rhythms that, in turn, reinforce the circadian clock network itself to anticipate and orchestrate metabolic responses to food intake. Eating is tightly interconnected with the circadian clock and recent evidence shows that the timing of meals is crucial for the control of appetite and metabolic regulation. Obesity results from combined long-term dysregulation in food intake (homeostatic and hedonic circuits), energy expenditure, and energy storage. Increasing evidence supports that the loss of synchrony of daily rhythms significantly impairs metabolic homeostasis and is associated with obesity. This review presents an overview of mechanisms regulating food intake (homeostatic/hedonic) and focuses on the crucial role of the circadian clock on the metabolic response to eating, thus providing a fundamental research axis to maintain a healthy eating behavior.

Early time-restricted eating may favorably impact cognitive acuity in university students: a randomized pilot study

Cognitive acuity is important for academic success. The preliminary efficacy of early time-restricted eating (eTRE) on cognitive acuity was examined in a sample of university students attending a large southwestern university. It was hypothesized that adherence to eTRE would result in improved cognitive acuity as assessed by the Trail Making Tests (i.e., TMT-A and TMT-B) and the Stroop Color and Word Test. Participants were randomized to an intervention group (eTRE) with a daily 6-hour eating window or a control group (CON) with a daily 16-hour eating window; 24 participants initiated the study (13 eTRE and 11 CON). Blood ketones (i.e., β-hydroxybutyrate [BHB]) and brain-derived neurotrophic factor were also assessed. The 8-week intervention was forestalled by COVID-19 laboratory closures beginning in March 2020, and only data obtained at week 0 (baseline) and week 4 were viable for statistical analyses. Study attrition was high (50% for eTRE and 23% for CON). At week 4, there was a 27% and 6% decrease in TMT-B response time for the eTRE and CON groups, respectively (P = .02). TMT-B response time was inversely correlated to plasma BHB among participants (r = -0.633; P = .008). Considering the inverse relationship between TMT-B response time and plasma BHB, these preliminary data suggest that eTRE may improve some aspects of cognitive acuity in this population. Future investigations are needed to confirm these findings and should accommodate individual preferences regarding the initiation time of the eating window while also considering the impact on social influences and exercise engagement.

Chrononutrition-When We Eat Is of the Essence in Tackling Obesity

Obesity is a chronic and relapsing public health problem with an extensive list of associated comorbidities. The worldwide prevalence of obesity has nearly tripled over the last five decades and continues to pose a serious threat to wider society and the wellbeing of future generations. The pathogenesis of obesity is complex but diet plays a key role in the onset and progression of the disease. The human diet has changed drastically across the globe, with an estimate that approximately 72% of the calories consumed today come from foods that were not part of our ancestral diets and are not compatible with our metabolism. Additionally, multiple nutrient-independent factors, e.g., cost, accessibility, behaviours, culture, education, work commitments, knowledge and societal set-up, influence our food choices and eating patterns. Much research has been focused on 'what to eat' or 'how much to eat' to reduce the obesity burden, but increasingly evidence indicates that 'when to eat' is fundamental to human metabolism. Aligning feeding patterns to the 24-h circadian clock that regulates a wide range of physiological and behavioural processes has multiple health-promoting effects with anti-obesity being a major part. This article explores the current understanding of the interactions between the body clocks, bioactive dietary components and the less appreciated role of meal timings in energy homeostasis and obesity.

A qualitative exploration of facilitators and barriers of adherence to time-restricted eating

Time-restricted eating (TRE), a dietary strategy that involves limiting daily energy intake to a window of ≤12 h is appealing for weight management and metabolic health due to its relative simplicity and the ability to consume ad libitum diet during eating windows. Despite the potential utility of TRE for improving health and reducing disease, the feasibility of adherence depends upon a variety of multilevel factors which are largely unexplored. The primary aim of our study was to explore facilitators and barriers of adherence to TRE among community-dwelling individuals. Semi-structured qualitative interviews were conducted among 24 individuals (50% male; M age: 34, range: 18-57; 58% overweight/obese) who currently or formerly practiced TRE. Thematic analysis identified facilitators of and barriers to TRE adherence at multiple levels of influence (i.e., biological, behavioral, psychosocial, environmental). Key facilitators of adherence included improvements in physical health and energy levels, alignment with other aspects of diet, exercise and sleep patterns, self-monitoring and positive psychological impacts, social support, and busy or regular schedules. Key barriers included negative physical health effects, feelings of hunger and sluggishness, difficulty in skipping valued baseline eating routines or inadequate diet quality during the eating window, misalignment of TRE with 24-h activity behaviors, difficulties with self-monitoring, the need to mitigate negative feelings, social situations that discourage TRE, and irregular or idle schedules. Results illustrate that key drivers of adherence differ across individuals and their unique settings and that multiple drivers of behavior should be considered in the successful implementation of TRE. Findings may inform interventions seeking to tailor TRE schedules to fit individuals' diverse behavioral patterns and preferences, thereby optimizing adherence.

Are individual or group interventions more effective for long-term weight loss in adults with obesity? A systematic review

Guidelines recommend individual and group interventions for weight loss, based on preference. Our 2009 systematic review compared long-term effectiveness of individual or group approaches to the same intervention, but there are new randomized controlled trials (RCTs) of high-quality data. We updated and expanded our previous systematic review. We searched Medline and Embase from 1966 to May 2021, and a clinical trial register from 1966 to 2017. Review Manager (5.4.1) was used to conduct meta-analysis. Ten RCTs were included. The primary outcome, mean weight change at final follow-up, was -1.33 kg (95% confidence interval CI: -2.04, -0.62; 10 trials, 2169 participants), favouring group interventions (p < .001). For the secondary outcomes, attainment of ≥5% body weight loss at final follow-up, the risk ratio (RR) was 1.36 (95% CI 1.05, 1.77; three trials, 1520 participants), favouring group interventions (p = .02); attrition at final follow-up was similar between group and individual arms of trials, RR 0.93 (95% CI 0.82, 1.07) (p = .31). Group interventions can be more effective than individual interventions for long-term weight loss in adults with obesity. However, few studies were included in the clinically relevant, secondary outcome measures. Research on delivering group processes in weight management is needed.

Is time-restricted eating a robust eating regimen during periods of disruptions in daily life? A qualitative study of perspectives of people with overweight during COVID-19

Background

Time-restricted eating (TRE) has been suggested as a feasible dietary strategy in individuals with overweight. Disruptions in daily life e.g., severe illness can affect engagement in lifestyle interventions to obtain healthier body weight. This study examined if and how the engagement with TRE among people with overweight was affected by the Danish COVID-19 lockdowns as an example of disruptions in daily life.

Methods

Fifteen participants with overweight enrolled in a TRE intervention, i.e. restricting all eating and drinking except water to the same daily ten-hour window, were interviewed about their experiences and engagement with TRE during COVID-19 lockdowns. Interviews were semi-structured and conducted by phone or face-to-face with safe social distancing. Data analysis was grounded in a reflexive thematic analysis approach.

Results

Daily life rhythms were disrupted by lockdowns by preventing participants from performing ordinary daily activities such as going to work, socialising, eating out or exercising. For some, this challenged their TRE engagement, while most were able to undertake the TRE eating window but reported increased snacking and consumption of take-away food within their eating window. For all, exercise habits became unhealthier. The negative impact on TRE engagement primarily occurred during daytime, as social distancing made it easier to engage with TRE during evenings.

Conclusions

This study showed that even people highly motivated to obtain healthier lifestyles practices struggled to maintain engagement with healthy behaviours, whereas sticking to the TRE window was manageable during COVID-19. TRE as a weight loss strategy was challenged which calls for more attention to supporting people in daily life to obtain healthier practices, also in case of periods of other disruptions such as divorce, serious illness etc.

Obesity, cancer risk, and time-restricted eating

Obesity and the associated metabolic syndrome is considered a pandemic whose prevalence is steadily increasing in many countries worldwide. It is a complex, dynamic, and multifactorial disorder that presages the development of several metabolic, cardiovascular, and neurodegenerative diseases, and increases the risk of cancer. In patients with newly diagnosed cancer, obesity worsens prognosis, increasing the risk of recurrence and decreasing survival. The multiple negative effects of obesity on cancer outcomes are substantial, and of great clinical importance. Strategies for weight control have potential utility for both prevention efforts and enhancing cancer outcomes. Presently, time-restricted eating (TRE) is a popular dietary intervention that involves limiting the consumption of calories to a specific window of time without any proscribed caloric restriction or alteration in dietary composition. As such, TRE is a sustainable long-term behavioral modification, when compared to other dietary interventions, and has shown many health benefits in animals and humans. The preliminary data regarding the effects of time-restricted feeding on cancer development and growth in animal models are promising but studies in humans are lacking. Interestingly, several short-term randomized clinical trials of TRE have shown favorable effects to reduce cancer risk factors; however, long-term trials of TRE have yet to investigate reductions in cancer incidence or outcomes in the general population. Few studies have been conducted in cancer populations, but a number are underway to examine the effect of TRE on cancer biology and recurrence. Given the simplicity, feasibility, and favorable metabolic improvements elicited by TRE in obese men and women, TRE may be useful in obese cancer patients and cancer survivors; however, the clinical implementation of TRE in the cancer setting will require greater in-depth investigation.

The road ahead of dietary restriction on anti-aging: focusing on personalized nutrition

Dietary restriction (DR), including caloric restriction (CR), intermittent fasting (IF), and restriction of specific food compositions, can delay aging, and the main mechanisms include regulation of nutrient-sensing pathways and gut microbiota. However, the effects of DR regimens on longevity remain controversial, as some studies have demonstrated that IF, rather than CR or diet composition, influences longevity, while other studies have shown that the restricted-carbohydrate or -protein diets, rather than CR, determine health and longevity. Many factors, including DR-related factors (carbohydrate or protein composition, degree and duration of DR), and individual differences (health status, sex, genotype, and age of starting DR), would be used to explain the controversial anti-aging effects of DR, thus highlighting the necessity of precise DR intervention for anti-aging. Personalized DR intervention in humans is challenging because of the lack of accurate aging molecular biomarkers and vast individual variability. Using machine learning to build a predictive model based on the data set of clinical features, gut microbiome and metabolome, may be a good method to achieve precise DR intervention. Therefore, this review analyzed the anti-aging effects of various DR regimens, summarized their mechanisms and influencing factors, and proposed a future research direction for achieving personalized DR regimens for slowing aging.

The Effects of Intermittent Fasting and Continuous Energy Restriction with Exercise on Cardiometabolic Biomarkers, Dietary Compliance, and Perceived Hunger and Mood: Secondary Outcomes of a Randomised, Controlled Trial

(1) Background: Excess weight in the form of adiposity plays a key role in the pathogenesis of cardiometabolic diseases. Lifestyle modifications that incorporate continuous energy restriction (CER) are effective at inducing weight loss and reductions in adiposity; however, prescribing daily CER results in poor long-term adherence. Over the past decade, intermittent fasting (IF) has emerged as a promising alternative to CER that may promote increased compliance and/or improvements in cardiometabolic health parameters independent of weight loss. (2) Methods: This paper presents a secondary analysis of data from a 12-week intervention investigating the effects of a twice-weekly fast (5:2 IF; IFT group) and CER (CERT group) when combined with resistance exercise in 34 healthy participants (17 males and 17 females, mean BMI: 27.0 kg/m2, mean age: 23.9 years). Specifically, changes in cardiometabolic blood markers and ratings of hunger, mood, energy and compliance within and between groups were analysed. Dietary prescriptions were hypoenergetic and matched for energy and protein intake. (3) Results: Both dietary groups experienced reductions in total cholesterol (TC; mean reduction, 7.8%; p < 0.001), low-density lipoprotein cholesterol (LDL-C; mean reduction, 11.1%; p < 0.001) and high-density lipoprotein cholesterol (mean reduction 2.6%, p = 0.049) over the 12 weeks. Reductions in TC and LDL-C were greater in the IFT group after adjustment for baseline levels and change in weight. No significant changes in markers of glucose regulation were observed. Both groups maintained high levels of dietary compliance (~80%) and reported low levels of hunger over the course of the intervention period. (4) Conclusions: Secondary data analysis revealed that when combined with resistance training, both dietary patterns improved blood lipids, with greater reductions observed in the IFT group. High levels of compliance and low reported levels of hunger throughout the intervention period suggest both diets are well tolerated in the short-to-medium term.

Effects of Intermittent Energy Restriction Alone and in Combination with Sprint Interval Training on Body Composition and Cardiometabolic Biomarkers in Individuals with Overweight and Obesity

The popularity of intermittent fasting (IF) and high intensity (sprint) interval training (SIT) has increased in recent years amongst the general public due to their purported health benefits and feasibility of incorporation into daily life. The number of scientific studies investigating these strategies has also increased, however, very few have examined the combined effects, especially on body composition and cardiometabolic biomarkers, which is the primary aim of this investigation. A total of thirty-four male and female participants (age: 35.4 ± 8.4 y, body mass index (BMI): 31.3 ± 3.5 kg/m2, aerobic capacity (VO2peak) 27.7 ± 7.0 mL·kg−1·min−1) were randomized into one of three 16-week interventions: (1) 5:2 IF (2 non-consecutive days of fasting per week, 5 days on ad libitum eating), (2) supervised SIT (3 bouts per week of 20s cycling at 150% VO2peak followed by 40 s of active rest, total 10 min duration), and (3) a combination of both interventions. Body composition, haemodynamic and VO2peak were measured at 0, 8 and 16 weeks. Blood samples were also taken and analysed for lipid profiles and markers of glucose regulation. Both IF and IF/SIT significantly decreased body weight, fat mass and visceral fat compared to SIT only (p < 0.05), with no significant differences between diet and diet + exercise combined. The effects of diet and/or exercise on cardiometabolic biomarkers were mixed. Only exercise alone or with IF significantly increased cardiorespiratory fitness. The results suggest that energy restriction was the main driver of body composition enhancement, with little effect from the low volume SIT. Conversely, to achieve benefits in cardiorespiratory fitness, exercise is required.

Intermittent Fasting: Potential Utility in the Treatment of Chronic Pain across the Clinical Spectrum

Dietary behavior can have a consequential and wide-ranging influence on human health. Intermittent fasting, which involves intermittent restriction in energy intake, has been shown to have beneficial cellular, physiological, and system-wide effects in animal and human studies. Despite the potential utility in preventing, slowing, and reversing disease processes, the clinical application of intermittent fasting remains limited. The health benefits associated with the simple implementation of a 12 to 16 h fast suggest a promising role in the treatment of chronic pain. A literature review was completed to characterize the physiologic benefits of intermittent fasting and to relate the evidence to the mechanisms underlying chronic pain. Research on different fasting regimens is outlined and an overview of research demonstrating the benefits of intermittent fasting across diverse health conditions is provided. Data on the physiologic effects of intermittent fasting are summarized. The physiology of different pain states is reviewed and the possible implications for intermittent fasting in the treatment of chronic pain through non-invasive management, prehabilitation, and rehabilitation following injury and invasive procedures are presented. Evidence indicates the potential utility of intermittent fasting in the comprehensive management of chronic pain and warrants further investigation.

Does intermittent fasting impact mental disorders? A systematic review with meta-analysis

Accumulating evidence supports the benefits of intermittent fasting (IF) as a dietary strategy for cardiometabolic health and weight control. However, little is known about the potential implications of IF on mental disorders. The aim of this review was to synthesize evidence regarding the effects of IF on mental disorders (depression, anxiety, and mood state) in the general population. We conducted a systematic search in five databases from inception to January 2022. Randomized and nonrandomized clinical trials (RCTs/nonRCTs) were included. A random effects method was used to pool standardized mean differences (SMDs) and 95% CIs. A total of 14 studies involving 562 individuals were included, of which 8 were RCTs and 6 were nonRCTs. IF showed a moderate and positive effect on depression scores when compared to control groups (SMD: 0.41; 95%CI: 0.05 to 0.76; I2=45%; n = 4). Conversely, within-group analyses did not show any significant effect of IF on anxiety (SMD: 0.10; 95%CI: -0.09 to 0.30; I2=0%; n = 5) or mood state (SMD: 0.14; 95%CI: -0.09 to 0.37; I2=59%; n = 7). IF modalities did not negatively impact mental disorders in the general population. In fact, IF showed a positive influence on diminishing depression scores, and did not modify anxiety or mood.

The Fasting and Shifted Timing (FAST) of Eating Study: A pilot feasibility randomized crossover intervention assessing the acceptability of three different fasting diet approaches

BACKGROUND AND AIMS

The aim of this study is to assess the acceptability of following three different fasting protocols [Early Time-restricted Feeding (eTRF; eating majority of kcals before 5pm), Time-restricted Feeding (TRF; restricting feeding window to 8 h/d), or Alternate Day Fasting (ADF; complete fasting every other day)].

METHODS

In this remotely delivered six-week crossover intervention, participants were randomly assigned to follow either an eTRF, TRF, or ADF diet for one week, followed by a one-week washout period. Participants followed all three diets and completed questionnaires assessing self-reported weight, energy intake, dietary acceptability (Food Acceptability Questionnaire), and facilitators and barriers to adhering to each diet. Differences in main outcomes (e.g., dietary acceptability and weight loss) were assessed via repeated measures ANOVA.

RESULTS

A total of 32 of participants began the study (mean BMI of 32.6 ± 6.0 kg/m²). There were no differences in kcals or weight loss among the three diets. Dietary acceptability was higher on the TRF diet (54.1 ± 8.2) than the eTRF (50.2 ± 6.6, p = 0.02) or ADF (48.0 ± 7.9, p = 0.004) diets. The majority of participants (71%) indicated the TRF diet was the easiest to follow and 75% said that ADF was the most difficult. Participants cited having a mobile app to track their diet and being provided with menu plans would help facilitate adherence with their diets.

CONCLUSIONS

This study found that acceptability was highest for an TRF diet and lowest for ADF, with no differences in weight loss or change in energy intake among the TRF, ADF, or eTRF groups.

CLINICAL TRIALS

GOV IDENTIFIER

NCT04527952.

Time-Restricted Feeding Studies and Possible Human Benefit

Metabolic syndrome consists of a constellation of clinical factors associated with an increased risk of cardiovascular disease, type 2 diabetes, and cancer. Preclinical studies demonstrate that restricting the time during a 24-hour period when an obese animal eats (time-restricted feeding) leads to metabolic benefits. These benefits, which may or may not be associated with weight loss, often lead to improvements in glucose tolerance and insulin sensitivity. Studies seeking to determine whether similar benefits result when humans restrict daily eating time (time-restricted eating) are less mature and less consistent in their findings. In this commentary, we outline some of the exciting preclinical findings, the challenges that preliminary studies in humans present, and efforts of the US National Institutes of Health and specifically the National Cancer Institute to address the role of time-restricted eating in cancer.

Effects of Intermittent Fasting in Human Compared to a Non-intervention Diet and Caloric Restriction: A Meta-Analysis of Randomized Controlled Trials

Background

The popularity of applying intermittent fasting (IF) has increased as more and more people are trying to avoid or alleviate obesity and metabolic disease. This study aimed to systematically explore the effects of various IF in humans.

Methods

The randomized controlled trials (RCTs) related to IF vs. non-intervention diet or caloric restriction (CR) were retrieved in PubMed, Web of Science, Cochrane Library database, and Embase. Extraction outcomes included, but were not limited to, weight, body mass index (BMI), waist circumference (WC), fasting glucose, and triglyceride (TG).

Results

This study includes 43 RCTs with 2,483 participants. The intervention time was at least 1 month, and the median intervention time was 3 months. Contrasting results between IF and non-intervention diet showed that participants had lower weight (weighted mean difference (WMD) = 1.10, 95% CI: 0.09–2.12, p = 0.03) and BMI after IF (WMD = 0.38, 95% CI: 0.08–0.68, p = 0.01). The WC of participants after IF decreased significantly compared with the non-intervention diet (WMD = 1.02, 95% CI: 0.06–1.99, p = 0.04). IF regulated fat mass (FM) more effectively than non-intervention diet (WMD = 0.74, 95% CI: 0.17–1.31, p = 0.01). The fat-free mass of people after IF was higher (WMD = −0.73, 95% CI: (−1.45)–(−0.02), p = 0.05). There was no difference in fasting blood glucose concentrations between participants in the after IF and non-intervention diet groups. The results of insulin concentrations and HOMA-IR, though, indicated that IF was significantly more beneficial than non-intervention diet (standard mean difference (SMD) = −0.21, 95% CI: 0.02–0.40, p = 0.03, and WMD = 0.35, 95% CI: 0.04–0.65, p = 0.03, respectively). Cholesterol and TG concentrations in participants after IF were also lower than that after a nonintervention diet (SMD = 0.22, 95% CI: 0.09–0.35, p = 0.001 and SMD = 0.13, 95% CI: 0.00–0.26, p = 0.05, respectively). IF outcomes did not differ from CR except for reduced WC.

Conclusion

Intermittent fasting was more beneficial in reducing body weight, WC, and FM without affecting lean mass compared to the non-intervention diet. IF also effectively improved insulin resistance and blood lipid conditions compared with non-intervention diets. However, IF showed less benefit over CR.

What happens after a weight loss intervention? A qualitative study of drivers and challenges of maintaining time-restricted eating among people with overweight at high risk of type 2 diabetes

Time-restricted eating (TRE)¹ has been conceptualised as a strategy for achieving weight loss and improving metabolic health, but limited knowledge exists about how people can maintain TRE in daily life. This study examined how TRE was maintainable in daily life after a three-month intervention (the RESET study) in which participants were encouraged to consume all food and beverages except water within a 10-hour daily window. Specifically, we examined TRE maintenance patterns across participants, including drivers and challenges for maintenance success. A qualitative longitudinal study was conducted, and twenty participants with overweight at high risk of type 2 diabetes were interviewed using a semi-structured interview guide at the end of the intervention and after a three-month follow-up period. Data were analysed longitudinally in two steps inspired by a pattern-oriented longitudinal analysis approach. Seven participants maintained a strict 10-hour window, ten maintained an adjusted TRE regimen (e.g., taking days off), and three did not attempt maintenance. Maintenance drivers included consistent daily rhythms and regular meal patterns, subjective experiences (e.g., feeling healthier), making flexible adjustments to the TRE regimen, family support and avoiding feelings of guilt. Maintenance challenges included social evening events, inconsistent daily rhythms and eating patterns, preoccupation with losing weight, lack of family support and self-blame. TRE was manageable for most participants; however, personalised support for adjusting TRE to daily life is needed to ensure long-term maintenance. Future studies should explore the effectiveness of a personalised TRE concept to determine the usefulness of TRE in real-life settings.

Heart-Healthy Diets and the Cardiometabolic Jackpot

This review highlights the key components of a heart-healthy diet and presents an evidence-based overview of recent research. Diets that increase plant-based food sources and healthy unsaturated fats consumption and limit foods that are processed and/or high in sodium, refined sugar, and saturated fat are recommended. Dietary modification can be supplemented with lifestyle-based therapies (eg, exercise, time-restricted eating) to maximize clinical benefit and achieve the "cardiometabolic jackpot." Physicians should take into account cultural preferences, affordability and accessibility of foods, and their patients' cultural values or expectations when recommending dietary interventions.

Perspective: Time-Restricted Eating-Integrating the What with the When

Time-restricted eating (TRE) is a popular dietary strategy that emphasizes the timing of meals in alignment with diurnal circadian rhythms, permitting ad libitum energy intake during a restricted (∼8-10 h) eating window each day. Unlike energy-restricted diets or intermittent fasting interventions that focus on weight loss, many of the health-related benefits of TRE are independent of reductions in body weight. However, TRE research to date has largely ignored what food is consumed (i.e., macronutrient composition and energy density), overlooking a plethora of past epidemiological and interventional dietary research. To determine some of the potential mechanisms underpinning the benefits of TRE on metabolic health, future studies need to increase the rigor of dietary data collected, assessed, and reported to ensure a consistent and standardized approach in TRE research. This Perspective article provides an overview of studies investigating TRE interventions in humans and considers dietary intake (both what and when food is eaten) and their impact on selected health outcomes (i.e., weight loss, glycemic control). Integrating existing dietary knowledge about what food is eaten with our recent understanding on when food should be consumed is essential to optimize the impact of dietary strategies aimed at improving metabolic health outcomes.

Satiety Associated with Calorie Restriction and Time-Restricted Feeding: Central Neuroendocrine Integration

This review focuses on summarizing current knowledge on how time-restricted feeding (TRF) and continuous caloric restriction (CR) affect central neuroendocrine systems involved in regulating satiety. Several interconnected regions of the hypothalamus, brainstem, and cortical areas of the brain are involved in the regulation of satiety. Following CR and TRF, the increase in hunger and reduction in satiety signals of the melanocortin system [neuropeptide Y (NPY), proopiomelanocortin (POMC), and agouti-related peptide (AgRP)] appear similar between CR and TRF protocols, as do the dopaminergic responses in the mesocorticolimbic circuit. However, ghrelin and leptin signaling via the melanocortin system appears to improve energy balance signals and reduce hyperphagia following TRF, which has not been reported in CR. In addition to satiety systems, CR and TRF also influence circadian rhythms. CR influences the suprachiasmatic nucleus (SCN) or the primary circadian clock as seen by increased clock gene expression. In contrast, TRF appears to affect both the SCN and the peripheral clocks, as seen by phasic changes in the non-SCN (potentially the elusive food entrainable oscillator) and metabolic clocks. The peripheral clocks are influenced by the primary circadian clock but are also entrained by food timing, sleep timing, and other lifestyle parameters, which can supersede the metabolic processes that are regulated by the primary circadian clock. Taken together, TRF influences hunger/satiety, energy balance systems, and circadian rhythms, suggesting a role for adherence to CR in the long run if implemented using the TRF approach. However, these suggestions are based on only a few studies, and future investigations that use standardized protocols for the evaluation of the effect of these diet patterns (time, duration, meal composition, sufficiently powered) are necessary to verify these preliminary observations.

Effects of Intermittent Fasting on Cardiometabolic Health: An Energy Metabolism Perspective

This review summarizes the effects of different types of intermittent fasting (IF) on human cardiometabolic health, with a focus on energy metabolism. First, we discuss the coordinated metabolic adaptations (energy expenditure, hormonal changes and macronutrient oxidation) occurring during a 72 h fast. We then discuss studies investigating the effects of IF on cardiometabolic health, energy expenditure and substrate oxidation. Finally, we discuss how IF may be optimized by combining it with exercise. In general, IF regimens improve body composition, ectopic fat, and classic cardiometabolic risk factors, as compared to unrestricted eating, especially in metabolically unhealthy participants. However, it is still unclear whether IF provides additional cardiometabolic benefits as compared to continuous daily caloric restriction (CR). Most studies found no additional benefits, yet some preliminary data suggest that IF regimens may provide cardiometabolic benefits in the absence of weight loss. Finally, although IF and continuous daily CR appear to induce similar changes in energy expenditure, IF regimens may differentially affect substrate oxidation, increasing protein and fat oxidation. Future tightly controlled studies are needed to unravel the underlying mechanisms of IF and its role in cardiometabolic health and energy metabolism.

Time-Limited Eating and Continuous Glucose Monitoring in Adolescents with Obesity: A Pilot Study

Due to its simplicity, time-limited eating (TLE) may represent a more feasible approach for treating adolescents with obesity compared to other caloric restriction regimens. This pilot study examines the feasibility and safety of TLE combined with continuous glucose monitoring (CGM) in adolescents. Fifty adolescents with BMI ≥95th percentile were recruited to complete a 12-week study. All received standard nutritional counseling, wore a CGM daily, and were randomized to: (1) Prolonged eating window: 12 h eating/12 h fasting + blinded CGM; (2) TLE (8 h eating/16 h fasting, 5 days per week) + blinded CGM; (3) TLE + real-time CGM feedback. Recruitment, retention, and adherence were recorded as indicators of feasibility. Weight loss, dietary intake, physical activity, eating behaviors, and quality of life over the course of the intervention were explored as secondary outcomes. Forty-five participants completed the study (16.4 ± 1.3 years, 64% female, 49% Hispanic, 75% public insurance). There was high adherence to prescribed eating windows (TLE 5.2 d/wk [SD 1.1]; control 6.1 d/wk [SD 1.4]) and daily CGM wear (5.85 d/wk [SD 4.8]). Most of the adolescents (90%) assigned to TLE reported that limiting their eating window and wearing a CGM was feasible without negative impact on daily functioning or adverse events. There were no between-group difference in terms of weight loss, energy intake, quality of life, physical activity, or eating behaviors. TLE combined with CGM appears feasible and safe among adolescents with obesity. Further investigation in larger samples, with a longer intervention duration and follow-up assessments are needed.

Associations between Fasting Duration, Timing of First and Last Meal, and Cardiometabolic Endpoints in the National Health and Nutrition Examination Survey

Background: Research indicates potential cardiometabolic benefits of energy consumption earlier in the day. This study examined the association between fasting duration, timing of first and last meals, and cardiometabolic endpoints using data from the National Health and Nutrition Examination Survey (NHANES). Methods: Cross-sectional data from NHANES (2005–2016) were utilized. Diet was obtained from one to two 24-h dietary recalls to characterize nighttime fasting duration and timing of first and last meal. Blood samples were obtained for characterization of C-reactive protein (CRP); glycosylated hemoglobin (HbA1c %); insulin; glucose; and high-density lipoprotein (HDL), low-density lipoprotein (LDL), and total cholesterol. Survey design procedures for adjusted linear and logistic regression were performed. Results: Every one-hour increase in nighttime fasting duration was associated with a significantly higher insulin and CRP, and lower HDL. Every one-hour increase in timing of the last meal of the day was statistically significantly associated with higher HbA1c and lower LDL. Every one-hour increase in first mealtime was associated with higher CRP (β = 0.044, p = 0.0106), insulin (β = 0.429, p < 0.01), and glucose (β = 0.662, p < 0.01), and lower HDL (β = −0.377, p < 0.01). Conclusion: In this large public health dataset, evidence for the beneficial effect of starting energy consumption earlier in the day on cardiometabolic endpoints was observed.

Time-Restricted Eating Improves Quality of Life Measures in Overweight Humans

Time-restricted eating (TRE) reduces weight in humans, but its effects on quality of life have not been well characterized. By performing a secondary analysis of a randomized clinical trial, we examined the effects of TRE (12-week intervention, 8 h eating window) vs. non-TRE (unrestricted eating) on quality of life (QoL) measures. Twenty subjects with overweight and prolonged eating window (mean (SD): 15.4 h (0.9)) were randomized to either 12 weeks of TRE (8 h eating window: (n = 11)) or non-TRE (n = 9). QoL data were collected with the 36-item Short Form Survey (SF-36) pre- and post-intervention. Given a two-way ANOVA model and post-hoc t-test analysis, the TRE group improved limitations due to emotional health post-intervention: +97.0 (10.0)) vs. baseline: +66.7 (42.2) (p = 0.02) and perceived change in health over the last year end intervention: +68.2 (16.2) vs. baseline: +52.3 (23.6) (p = 0.001) relative to baseline. The TRE group improved limitations due to emotional health TRE: +97.0 (10.0) vs. non-TRE: +55.6 (44.1) (p = 0.05) and perceived change in health (TRE: +68.2 (16.2) vs. non-TRE: +44.4 (31.6) (p = 0.04) relative to the non-TRE group at post-intervention (p < 0.025). In conclusion, 12 weeks of TRE does not adversely affect QoL and may be associated with modest improvements in QoL relative to baseline and unrestricted eating; these findings support future studies examining TRE compliance and durability.