Missing puzzle pieces of time-restricted-eating (TRE) as a long-term weight-loss strategy in overweight and obese people? A systematic review and meta-analysis of randomized controlled trials

Intermittent fasting for weight management and metabolic health: An updated comprehensive umbrella review of health outcomes

AIMS

To provide an updated comprehensive evaluation of the quality and evidence association of existing studies on health outcomes related to intermittent fasting (IF).

MATERIALS AND METHODS

We conducted a systematic search of PubMed, Web of Science, Cochrane Library, and Embase databases, covering literature up to June 2024. Meta-analyses and systematic reviews that include adult populations and quantitatively analyse health outcomes related to IF interventional studies are included. For evidence with complete data, we reanalyzed health evidence effect sizes and 95% confidence intervals using random-effects models. Article quality and the certainty of the evidence were graded using A Measurement Tool to Assess Systematic Reviews (AMSTAR-2), Grading of Recommendations Assessment, Development and Evaluation (GRADE) system, and a standardized credibility grading system.

RESULTS

Twelve meta-analysis studies and 122 health outcome associations with IF were identified. High-quality evidence indicated significant associations between time-restricted eating (TRE) and weight loss, fat mass reduction, decreased fasting insulin and glycosylated haemoglobin levels in overweight or obese adults, as well as between the 5:2 diet and reduced low-density lipoprotein cholesterol levels. Moderate-to-low-quality evidence suggested associations between modified alternate-day fasting and improvements in body weight, lipid profile and blood pressure. Additionally, high-to-low-quality evidence showed that IF regimens effectively improved liver health in non-alcoholic fatty liver disease.

CONCLUSIONS

This umbrella review highlights IF, especially TRE, as a promising intervention for weight and metabolic health, particularly beneficial for overweight or obese adults. We also highlight the need for further extensive research to understand the long-term effects, individualized IF plans and potential adverse effects of IF in different populations.

Evaluating the effects of time-restricted eating on overweight and obese women with polycystic ovary syndrome: A randomized controlled trial study protocol

BACKGROUND

Time-restricted eating (TRE) manages weight effectively, but choosing how long and what time window remain debatable. Although an 8:00 a.m. to 16:00 p.m. time frame is reported to show positive results in most weight loss trial, its safety and efficacy in overweight and obese women with polycystic ovary syndrome (PCOS) is uncertain. This randomized controlled trial is conducted to evaluate the safety and efficacy of TRE in specific populations.

OBJECTIVE

This study aims to assess the 6-month effects of TRE on weight change, metabolic improvement, reproductive recovery, and health-related quality of life in overweight and obese women with polycystic ovary syndrome (PCOS), compared to those who did not receive TRE.

METHODS

This randomized controlled trial will enroll 96 overweight and obese women with polycystic ovary syndrome (PCOS), who will be randomly assigned to either a TRE group (with an eating window from 8:00 a.m. to 16:00 p.m.) or a control group (without eating time restrictions), with 49 participants in each group. Evaluators and data analysts will remain blinded to group allocation throughout the study. The primary outcomes, including changes in weight and body mass index (BMI), will be assessed weekly. Secondary outcomes, encompassing alterations in sex hormones, metabolic parameters, body composition, sleep quality, quality of life, anxiety, and depression, will be evaluated monthly. Compliance and safety will be continuously monitored throughout the study. Additionally, a 6-month follow-up will be conducted at the end of the trial to assess the long-term effects of TRE. Statistical analysis will include the Anderson-Darling test for normality, T-test/Wilcoxon test based on distribution, mixed-effects models for assessing time/group effects, Cox model for time-to-event analysis, repeated ANOVA for change analysis, and sensitivity analysis. All tests will be conducted using appropriate software, with a significance level set at P<0.05. Missing data will be imputed.

DISCUSSION

The purpose of this study protocol is to further evaluate the effects of TRE in overweight and obese women with PCOS through a randomized controlled trial (RCT). Findings from this study are expected to provide new dietary intervention strategies for overweight and obese PCOS participants.

ETHICS AND DISSEMINATION

This study has received ethics approval from the Medical Ethics Committee of the University of South China (Number: NHHL027). Participants are included after signing informed consent. Results will be submitted for publication in peer-reviewed journals.

TRAIL REGISTRATION

Trail registration number: ChiCTR2400086815.

Effects of different types of intermittent fasting on metabolic outcomes: an umbrella review and network meta-analysis

BACKGROUND

Intermittent fasting (IF) holds promise for enhancing metabolic health. However, the optimum IF forms and their superiority over continuous energy restriction (CER) remain unclear due to disconnected findings.

METHODS

We systematically searched PubMed, Embase, and the Cochrane databases for meta-analyses of randomized controlled trials (RCTs) investigating the association between IF and metabolic health outcomes. Subsequently, we performed an umbrella review and network meta-analysis (NMA) to evaluate the efficacy of different forms of IF (time-restricted eating (TRE), alternate-day fasting (ADF), and 5:2 diet (regular eating for 5 days and energy restriction for 2 days per week)) compared to CER and usual diets on metabolic health outcomes. To assess the certainty of both direct and indirect estimates, we employed the Confidence in Network Meta-Analysis (CINeMA) approach. Additionally, we calculated the surface under the cumulative ranking curve (SUCRA) for each dietary strategy to determine their ranking in terms of metabolic health benefits.

RESULTS

Ten of the best and non-redundant meta-analysis studies, involving 153 original studies and 9846 participants, were included. When considering direct evidence only, all IF forms significantly reduced body weight compared to usual diets. In NMA incorporating indirect evidence, all IF regimens also significantly reduced body weight compared to usual diets. In the SUCRA of NMA, IF ranked higher than usual diets or CER in 85.4% and 56.1% of the outcomes, respectively. ADF had the highest overall ranking for improving metabolic health (ranked first: 64.3%, ranked second: 14.3%).

CONCLUSIONS

Overall, all IF forms demonstrate potentials to improve metabolic health, with ADF appearing to produce better outcomes across investigated outcomes. Further high-quality trials are warranted to confirm the (relative) efficacy of IF on metabolic health.

TRIAL REGISTRATION

PROSPERO (record no: CRD42022302690).

Meal Timing and Anthropometric and Metabolic Outcomes: A Systematic Review and Meta-Analysis

Importance

Meal timing strategies, such as time-restricted eating (TRE), reducing meal frequency, or altering calorie distribution across the day, have gained interest for their potential to enhance weight loss and metabolic health, particularly in managing chronic diseases, yet their long-term benefits are not known.

Objective

To evaluate the association between meal timing strategies (≥12 weeks) and anthropometric and metabolic indicators.

Data Sources

Medline, Embase, CINAHL, and Cochrane CENTRAL were searched from inception to October 17, 2023.

Study Selection

Randomized clinical trials, regardless of language and publication date, involving adults 18 years and older, evaluating within-day meal timing patterns for 12 or more weeks, and reporting anthropometric measures were included. Studies were excluded if participants had eating disorders, prior significant weight change, underwent bariatric surgery, were pregnant, or if controlled variables differed between groups.

Data Extraction and Synthesis

Study quality was determined via Risk of Bias 2.0 tool. Data were extracted independently by multiple reviewers. Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were used. Meta-analysis was performed using random-effects model on pooled continuous outcomes with 2 or more studies.

Main Outcome and Measures

Weight change in kilograms, reported as between-group mean difference with 95% CIs.

Results

Sixty-nine reports of 29 randomized clinical trials including 2485 individuals (1703 [69%] female; mean [SD] age, 44 [9.5] years; and mean [SD] body mass index, 33 [3.5]) were included. Study interventions included TRE (17 studies), meal frequency (8 studies), and calorie distribution (4 studies). There were some concerns of risk of bias for 7 studies and high concerns for 22 studies. Statistically significant weight change was observed in TRE when compared with control (-1.37 kg; 95% CI, -1.99 to -0.75 kg). Lower meal frequency and earlier caloric distribution were also both associated with greater change (-1.85 kg; 95% CI, -3.55 to -0.13 kg; and -1.75 kg; 95% CI, -2.37 to -1.13 kg, respectively).

Conclusions and Relevance

The findings of this meta-analysis suggest that TRE, lower meal frequency, and earlier caloric distribution in the day may reduce weight compared with standard care and/or nutritional advice; however, the effect sizes found were small and of uncertain clinical importance. High heterogeneity and risk of bias among included studies led to concerns about the certainty of the underpinning evidence. Further research, including trials with larger sample sizes, standardized interventions with prescribed or matched energy intake, and longer follow-up, are needed.

Comparing the effects of time-restricted eating on glycaemic control in people with type 2 diabetes with standard dietetic practice: A randomised controlled trial

AIMS

To test the efficacy of time-restricted eating (TRE) in comparison to dietitian-led individualised dietary guidance to improve HbA1c in people with Type 2 diabetes mellitus.

METHODS

In a parallel groups design, 51 adults (35-65 y) with Type 2 diabetes mellitus and overweight/obesity (HbA1c ≥6.5% (48 mmol/mol), BMI ≥25-≤40 kg/m2) commenced a six-month intervention. Following baseline, participants were randomised to TRE (1000-1900 h) or DIET (individualised dietetic guidance) with four consultations over four months. Changes in HbA1c (primary), body composition, and self-reported adherence (secondary) were analysed using linear mixed models. A non-inferiority margin of 0.3% (4 mmol/mol) HbA1c was set a priori.

RESULTS

Forty-three participants (56 ± 8 y, BMI: 33 ± 5 kg/m2, HbA1c: 7.6 ± 0.8%) completed the intervention. HbA1c was reduced (P=0.002; TRE: -0.4% (-5 mmol/mol), DIET: -0.3% (-4 mmol/mol)) with no group or interaction effects; TRE was non-inferior to DIET (-0.11%, 95%CI: -0.50% to 0.28%). Body mass reduced in both groups (TRE: -1.7 kg; DIET: -1.2 kg) via ∼900 kJ/d spontaneous energy reduction (P<0.001). Self-reported adherence was higher in TRE versus DIET (P<0.001).

CONCLUSIONS

When individualised dietary guidance is not available, effective, and/or suitable, TRE may be an alternative dietary strategy to improve glycaemic control in people with Type 2 diabetes mellitus.

The Effects of Time-Restricted Eating on Fat Loss in Adults with Overweight and Obese Depend upon the Eating Window and Intervention Strategies: A Systematic Review and Meta-Analysis

Time-restricted eating (TRE) is a circadian rhythm-based intermittent fasting intervention that has been used to treat obesity. However, the efficacy and safety of TRE for fat loss have not been comprehensively examined and the influences of TRE characteristics on such effects are unknown. This systematic review and meta-analysis comprehensively characterized the efficacy and safety of TRE for fat loss in adults with overweight and obese, and it explored the influence of TRE characteristics on this effect.

METHODS

A search strategy based on the PICOS principle was used to find relevant publications in seven databases. The outcomes were body composition, anthropometric indicators, and blood lipid metrics. Twenty publications (20 studies) with 1288 participants, covering the period from 2020 to 2024, were included.

RESULTS

Compared to the control group, TRE safely and significantly reduced body fat percentage, fat mass, lean mass, body mass, BMI, and waist circumference (MDpooled = -2.14 cm, 95% CI = -2.88~-1.40, p < 0.001), and increased low-density lipoprotein (LDL) (MDpooled = 2.70, 95% CI = 0.17~5.22, p = 0.037), but it did not alter the total cholesterol, high-density lipoprotein, and triglycerides (MDpooled = -1.09~1.20 mg/dL, 95% CI -4.31~5.47, p > 0.05). Subgroup analyses showed that TRE only or TRE-caloric restriction with an eating window of 6 to 8 h may be appropriate for losing body fat and overall weight.

CONCLUSIONS

This work provides moderate to high evidence that TRE is a promising dietary strategy for fat loss. Although it may potentially reduce lean mass and increase LDL, these effects do not pose significant safety concerns. This trial was registered with PROSPERO as CRD42023406329.

Comparing caloric restriction regimens for effective weight management in adults: a systematic review and network meta-analysis

BACKGROUND

Randomized controlled trials have confirmed the effectiveness of four prevalent caloric restriction regimens in reducing obesity-related health risks. However, there is no consensus on the optimal regimen for weight management in adults.

METHODS

We systematically searched PubMed, Embase, Web of Science, and Cochrane CENTRAL up to January 15, 2024, for randomized controlled trials (RCT) involving adults, evaluating the weight-loss effects of alternate day fasting (ADF), short-term fasting (STF), time-restricted eating (TRE), and continuous energy restriction (CER). The primary outcome was body weight, with secondary outcomes including BMI, fat mass, lean mass, waist circumference, fasting glucose, HOMA-IR, and adverse events. Bayesian network meta-analysis was conducted, ranking regimens using the surface under the cumulative ranking curve and the probability of being the best. Study quality was assessed using the Confidence in Network Meta-Analysis tool.

RESULTS

Data from 47 RCTs (representing 3363 participants) were included. ADF showed the most significant body weight loss (Mean difference (MD): -3.42; 95% Confidence interval (CI): -4.28 to -2.55), followed by TRE (MD: -2.25; 95% CI: -2.92 to -1.59). STF (MD: -1.87; 95% CI: -3.32 to -0.56) and CER (MD: -1.59; 95% CI: -2.42 to -0.79) rank third and fourth, respectively. STF lead to decline in lean mass (MD: -1.26; 95% CI: -2.16, -0.47). TRE showed benefits on fasting glucose (MD: -2.98; 95% CI: -4.7, -1.26). Subgroup analysis revealed all four caloric restriction regimens likely lead to modest weight loss after 1-3 months, with ADF ranked highest, but by 4-6 months, varying degrees of weight regain occur, particularly with CER, while interventions lasting 7-12 months may result in effective weight loss, with TRE potentially ranking first during both the 4-6 months and 7-12 months periods. ADF showing fewer and shorter-lasting physical symptoms.

CONCLUSION

All four included regiments were effective in reducing body weight, with ADF likely having the most significant impact. Each regimen likely leads to modest weight loss after 1-3 months, followed by weight regain by 4-6 months. However, interventions lasting 7-12 months achieve greater weight loss overall.

TRIAL REGISTRATION

PROSPERO: CRD42022382478.

Counting hours or calories? Metabolic regulatory role of time-restricted eating in adults with overweight and obesity: a systematic review and meta-analysis

Time-restricted eating (TRE) effectively improves healthspan, including controlling obesity and improving metabolic health. To date, few meta-analyses have been conducted to explore the effects of various protocols of TRE in participants with overweight/obesity. PubMed, Embase and the Cochrane Central Register of Controlled Trials were searched up until October 15, 2022. Randomized and non-randomized clinical trials that investigated the effect of TRE on body weight, body composition and cardiometabolic parameters in participants with overweight/obesity were included. Mean differences of changes from the baseline were used for all analyses between the two groups. Prespecified subgroup analyses based on different protocols of TRE were performed. Twenty-three studies were included in the meta-analysis with 1867 participants. TRE interventions led to significant changes in body weight. When energy restriction strategies were conducted in both the TRE and control groups, the weight-loss effect of TRE remained significant. TRE with 4 ∼ 8h feeding window, morning or late eating strategies, led to reduction in body weight and fat mass for at least 8 wk. Hence TRE is a potential and effective approach for weight loss for participants with overweight/obesity. An 8h-TRE intervention with a morning eating strategy for at least eight weeks might be the optimum TRE intervention mode.

Challenges in Providing an Overview of Results of Intermittent Fasting Interventions on Diabetes Parameters. Comment on Silva et al. Effects of Intermittent Fasting on Regulation of Metabolic Homeostasis: A Systematic Review and Meta-Analysis in Health and Metabolic-Related Disorders. J. Clin. Med. 2023, 12, 3699

We hereby comment on the systematic review "Effects of Intermittent Fasting on Regulation of Metabolic Homeostasis: A Systematic Review and Meta-Analysis in Health and Metabolic-Related Disorders" by Silva et al [...].

Beneficial effects of time-restricted fasting on cardiovascular disease risk factors: a meta-analysis

BACKGROUND

Cardiovascular disease continues to be a leading cause of mortality worldwide, highlighting the need to explore innovative approaches to improve cardiovascular health outcomes. Time-restricted fasting (TRF) is a dietary intervention that involves limiting the time window for food consumption. It has gained attention for its potential benefits on metabolic health and weight management. This study aims to investigate the impact of TRF on key risk factors, including body weight, glucose metabolism, blood pressure, and lipid profile.

METHODS

We conducted a systematic search in five databases (Scopus, Embase, PubMed, Cochrane, and Web of Science) for relevant studies up to January 2023. After applying inclusion criteria, 12 studies were eligible for analysis. Quality assessment was conducted using the ROB-2.0 tool and ROBINS-I. Risk of bias was mapped using Revman 5.3, and data analysis included Hartung-Knapp adjustment using R 4.2.2.

RESULTS

The group that underwent the TRF intervention exhibited a significant decrease in body weight (SMD: -0.22; 95%CI: -0.41, -0.04; P < 0.05) and fat mass (SMD: -0.19; 95%CI: -0.36, -0.02; P < 0.05), while maintaining lean mass (SMD: -0.09; 95%CI: -0.08, 0.26; P > 0.05).

CONCLUSION

TRF has shown potential as a treatment strategy for reducing total body weight by targeting adipose tissue, with potential improvements in cardiometabolic function.

Intermittent fasting and health outcomes: an umbrella review of systematic reviews and meta-analyses of randomised controlled trials

Background

Benefits of Intermittent fasting (IF) on health-related outcomes have been found in a range of randomised controlled trials (RCTs). Our umbrella review aimed to systematically analyze and synthesize the available causal evidence on IF and its impact on specific health-related outcomes while evaluating its evidence quality.

Methods

We comprehensively searched the PubMed, Embase, Web of Science, and Cochrane databases (from inception up to 8 January 2024) to identify related systematic reviews and meta-analyses of RCTs investigating the association between IF and human health outcomes. We recalculated the effect sizes for each meta-analysis as mean difference (MD) or standardized mean difference (SMD) with corresponding 95% confidence intervals (CIs). Subgroup analyses were performed for populations based on three specific status: diabetes, overweight or obesity, and metabolic syndrome. The quality of systematic reviews was evaluated using A Measurement Tool to Assess Systematic Reviews (AMSTAR), and the certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) system. This study is registered with PROSPERO (CRD42023382004).

Findings

A total of 351 associations from 23 meta-analyses with 34 health outcomes were included in the study. A wide range of outcomes were investigated, including anthropometric measures (n = 155), lipid profiles (n = 83), glycemic profiles (n = 57), circulatory system index (n = 41), appetite (n = 9), and others (n = 6). Twenty-one (91%) meta-analyses with 346 associations were rated as high confidence according to the AMSTAR criteria. The summary effects estimates were significant at p < 0.05 in 103 associations, of which 10 (10%) were supported by high certainty of evidence according to GRADE. Specifically, compared with non-intervention diet in adults with overweight or obesity, IF reduced waist circumference (WC) (MD = -1.02 cm; 95% CI: -1.99 to -0.06; p = 0.038), fat mass (MD = -0.72 kg; 95% CI: -1.32 to -0.12; p = 0.019), fasting insulin (SMD = -0.21; 95% CI: -0.40 to -0.02; p = 0.030), low-density lipoprotein cholesterol (LDL-C) (SMD = -0.20; 95% CI: -0.38 to -0.02; p = 0.027), total cholesterol (TC) (SMD = -0.29; 95% CI: -0.48 to -0.10; p = 0.003), and triacylglycerols (TG) (SMD = -0.23; 95% CI: -0.39 to -0.06; p = 0.007), but increased fat free mass (FFM) (MD = 0.98 kg; 95% CI: 0.18-1.78; p = 0.016). Of note, compared with the non-intervention diet, modified alternate-day fasting (MADF) reduced fat mass (MD = -0.70 kg; 95% CI: -1.38 to -0.02; p = 0.044). In people with overweight or obesity, and type 2 diabetes, IF increases high-density lipoprotein cholesterol (HDL-C) levels compared to continuous energy restriction (CER) (MD = 0.03 mmol/L; 95% CI: 0.01-0.05; p = 0.010). However, IF was less effective at reducing systolic blood pressure (SBP) than a CER diet in adults with overweight or obesity (SMD = 0.21; 95% CI: 0.05-0.36; p = 0.008).

Interpretation

Our findings suggest that IF may have beneficial effects on a range of health outcomes for adults with overweight or obesity, compared to CER or non-intervention diet. Specifically, IF may decreased WC, fat mass, LDL-C, TG, TC, fasting insulin, and SBP, while increasing HDL-C and FFM. Notably, it is worth noting that the SBP lowering effect of IF appears to be weaker than that of CER.

Funding

This work was supported by the National Key Research and Development Program of China (Q-JW), the Natural Science Foundation of China (Q-JW and T-TG), Outstanding Scientific Fund of Shengjing Hospital of China Medical University (Q-JW), and 345 Talent Project of Shengjing Hospital of China Medical University (T-TG).

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.

Metabolic changes with intermittent fasting

BACKGROUND

The prevalence of obesity is rising globally and effective strategies to treat obesity are needed. Intermittent fasting, a dietary intervention for weight management, has received growing interest from the general public, as well as healthcare professionals, as a form of lifestyle intervention.

METHODS

We executed a rapid review using PUBMED database to identify systematic reviews that examined the impact of intermittent fasting on metabolic indices, published between 2011 and 2022.

RESULTS

Intermittent fasting leads to weight loss of a similar magnitude to continuous energy restriction. Most of the evidence shows that intermittent fasting leads to greater fat loss as measured by fat mass (kg) or body fat percentage compared to an ad libitum diet, but fat loss attained during intermittent fasting is not significantly different to continuous energy restriction, although recent evidence shows intermittent fasting to be superior. There is mixed evidence for the impact of intermittent fasting on insulin resistance, fasting glucose and lipid profile. Some studies focused on populations of Muslim people, which showed that Ramadan fasting may lead to weight loss and improvement of metabolic parameters during fasting, although the effects are reversed when fasting is finished.

CONCLUSIONS

Intermittent fasting is more effective than an ad libitum dietary intake, and equally or more effective as continuous energy restriction, for weight management. However, there is inconclusive evidence on whether intermittent fasting has a clinically beneficial effect on glucose and lipid metabolism.

The effects of time-restricted eating for patients with nonalcoholic fatty liver disease: a systematic review

Nonalcoholic fatty liver disease (NAFLD) represents a significant global health concern. Numerous investigations have explored the implications of time-restricted eating (TRE) in the management of NAFLD. Therefore, the objective of our study was to conduct a systematic review to summarize and analyze all randomized controlled trials (RCTs) of TRE for patients with NAFLD. A thorough literature search was executed across Embase, Cochrane Library, and PubMed databases, covering all records from their inception until 1 September 2023. All clinical studies of TRE for NAFLD were summarized and analyzed. Our systematic review included four RCTs, encompassing a total of 443 NAFLD patients. These studies varied in sample size from 32 to 271 participants. The TRE intervention was consistently applied in an 8-h window, over durations ranging from 4 weeks to 12 months. The findings suggest that TRE could offer several health benefits for NAFLD patients, such as improved liver health indicators like liver stiffness and intrahepatic triglyceride (IHTG) levels. Consequently, TRE appears to be a promising dietary intervention for NAFLD patients. However, it is premature to recommend TRE for patients with NAFLD. The existing body of research on the effects of TRE in NAFLD contexts is limited, underscoring the need for further high-quality studies to expand our understanding of TRE's benefits in treating NAFLD. Ongoing clinical trials may provide more insights into the effects of TRE in NAFLD.

Time-Restricted Eating: A Novel Dietary Strategy for Cardiac Rehabilitation

Cardiac rehabilitation (CR) is a multimodal program considered to be the standard of care for secondary prevention of cardiovascular disease (CVD). The primary goals of CR are managing CVD risk factors and improving quality of life. Exercise is the cornerstone, but nutrition education delivered by registered dietitians (RDs) is a core component of CR. Yet patient constraints to adherence to dietary change and limited availability of RDs represent major barriers to the success of completion of nutrition intervention during CR. Therefore, nutritional strategies that reduce CVD risk factors, barriers to adherence, and have capacity for broad dissemination are warranted within CR programs. In this review, we propose time-restricted eating (TRE) as a nutrition strategy to improve the outcomes of CR by drawing on parallels to CVD in other populations and describe the available preliminary data on the efficacy of TRE for CVD. TRE is a dietary strategy that involves alternating periods of fasting and consumption of calories each day. We outline the feasibility, safety, and beneficial cardiometabolic impact of TRE from TRE research in other populations. We also discuss the potential for synergistic benefits of exercise when combined with TRE. Although there is currently limited research on TRE within CR programs, we highlight CR as a unique clinical setting where TRE could play a role in secondary prevention of CVD. Overall, we outline the potential of TRE as a promising nutrition strategy to enhance the benefits of CR.

Is time-restricted eating (8/16) beneficial for body weight and metabolism of obese and overweight adults? A systematic review and meta-analysis of randomized controlled trials

Time-restricted eating (TRE) is a new therapeutic strategy for the management of weight loss and dysmetabolic diseases. At present, TRE (8/16, 8 h eating:16 h fasting) is the most common form of TRE. Therefore, this meta-analysis included randomized controlled trials (RCTs) on TRE (8/16) in overweight and obese adults to determine its impact on body weight and metabolism. Articles reviewed from PubMed, Ovid MEDLINE, Embase, and Cochrane Central Register for the relevant RCTs that compared TRE (8/16) to non-TRE in overweight and obese adults. Eight RCTs were included in this meta-analysis. Participants following TRE (8/16) showed significant body weight reduction (mean difference [MD]: -1.48 kg, 95% confidence interval [CI]: -2.53 to -0.44) and fat mass reduction (MD: -1.09 kg, 95% CI: -1.55 to -0.63). There was no significant difference in lean mass change with TRE intervention (MD: -0.48 kg, 95% CI: -1.02 to 0.05, p = .08, I 2 = 41%). The energy restriction and early TRE (eTRE) subgroups resulted in greater weight loss. TRE (8/16) showed beneficial effects on the homeostatic model assessment of insulin resistance (HOMA-IR, MD: -0.32, 95% CI: -0.59 to -0.06), but had no significant effect on other parameters of glucose metabolism and lipid profiles. In conclusion, TRE (8/16), especially eTRE, or in combination with caloric intake restriction, is a potential therapeutic strategy for weight control in overweight and obese adults. TRE (8/16) also reduced HOMA-IR; therefore, it may have a positive effect on glucose metabolism.

Early time-restricted eating affects weight, metabolic health, mood, and sleep in adherent completers: A secondary analysis

OBJECTIVE

Data are mixed on whether intermittent fasting improves weight loss and cardiometabolic health. Here, the effects of time-restricted eating (TRE) in participants who consistently adhered ≥5 d/wk every week were analyzed.

METHODS

Ninety patients aged 25 to 75 years old with obesity were randomized to early TRE (eTRE; 8-hour eating window from 07:00 to 15:00) or a control schedule (≥12-hour window) for 14 weeks. A per-protocol analysis of weight loss, body composition, cardiometabolic health, and other end points was performed.

RESULTS

Participants who adhered to eTRE ≥5 d/wk every week had greater improvements in body weight (-3.7 ± 1.2 kg; p = 0.003), body fat (-2.8 ± 1.3 kg; p = 0.04), heart rate (-7 ± 3 beats/min; p = 0.02), insulin resistance (-2.80 ± 1.36; p = 0.047), and glucose (-9 ± 5 mg/dL; p = 0.047) relative to adherers in the control group. They also experienced greater improvements in mood, including fatigue and anger; however, they self-reported sleeping less and taking longer to fall asleep.

CONCLUSIONS

For those who can consistently adhere at least 5 d/wk, eTRE is a valuable approach for improving body weight, body fat, cardiometabolic health, and mood. Further research is needed to determine whether eTRE's effects of shortening sleep but reducing fatigue are healthful or not.

Health effects of the time-restricted eating in adults with obesity: A systematic review and meta-analysis

Background

The number of people suffering from overweight or obesity has been steadily increasing in recent years. As a new form of diet, the efficacy of time-restricted eating (TRE) remains debatable.

Objective

This meta-analysis quantified the effect of TRE on weight change and other physical parameters in obese and overweight adults.

Methods

We did a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing the TRE interventions on weight loss and other metabolic parameters by searching PubMed, Embase, and Cochrane Central Register of Controlled Trials to identify eligible trials published from database inception up until 23 August 2022. The risk of bias was assessed using the Revised Cochrane risk-of-bias tool (ROB-2.0). Meta-analysis was performed using Review Manager 5.4.1 software.

Results

Nine RCTs with 665 individuals (345 in the TRE group while 320 in the control group) were included. Results indicated that TRE had a greater decrease in body weight (-1.28 kg; 95% CI [-2.05, -0.52], p = 0.001), fat mass (-0.72 kg; 95% CI [-1.40, -0.03], p = 0.04), body mass index (-0.34 kg/m²; 95% CI [-0.64, -0.04], p = 0.03) and diastolic blood pressure (-2.26 mmHg 95% CI [-4.02, -0.50], p = 0.01). However, the meta-analysis demonstrated that there was no significant difference between TRE and the control group in lean mass, systolic blood pressure, waist circumference, fasting glucose, fasting insulin, homeostasis model assessment-insulin resistance (HOMA-IR), total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides. Besides, the duration of the study and daily eating window also had an impact on weight change.

Conclusion

TRE was associated with reductions in weight and fat mass and can be a dietary intervention option for adults with obesity. But high-quality trials and longer follow-ups are needed to draw definitive conclusions.

Time-restricted eating for patients with diabetes and prediabetes: A systematic review

Background

Several studies have explored the effect of time-restricted eating (TRE) on patients with diabetes and prediabetes. However, these studies have not been analyzed and summarized as a whole. We conducted a systematic review to summarize and analyze all studies about the efficacy and safety of TRE for patients with diabetes and prediabetes.

Methods

We conducted a comprehensive search of the Embase, PubMed and Cochrane databases and the time span was from inception to 1 May 2022. The Cochrane Collaboration's Risk of Bias 2 (RoB2) and ROBINS-I tools were used to evaluate the quality of included studies. The effect of TRE on weight loss, insulin sensitivity, plasma glucose, and the safety of TRE were summarized and analyzed.

Results

In total, 7 studies with 326 participants including 5 articles with 217 patients with diabetes and 2 articles with 109 patients with prediabetes were included. The TRE windows were from 4 to 10 h. The percentages of females ranged from 0 to 90%. The mean age ranged from 35.2 to 67.5 years, and most of patients adhered to TRE. All studies were assessed as high quality. TRE may result in weight loss, and improvements in the insulin sensitivity and plasma glucose, with no severe AEs.

Conclusion

Time-restricted eating is a safe and feasible intervention, and may offer cardiovascular and metabolic benefits for patients with diabetes and prediabetes. Studies in this field, which should be viewed as important, are limited. Therefore, more high-quality studies are needed.

Effectiveness of Early Time-Restricted Eating for Weight Loss, Fat Loss, and Cardiometabolic Health in Adults With Obesity: A Randomized Clinical Trial

Importance

It is unclear how effective intermittent fasting is for losing weight and body fat, and the effects may depend on the timing of the eating window. This randomized trial compared time-restricted eating (TRE) with eating over a period of 12 or more hours while matching weight-loss counseling across groups.

Objective

To determine whether practicing TRE by eating early in the day (eTRE) is more effective for weight loss, fat loss, and cardiometabolic health than eating over a period of 12 or more hours.

Design, Setting, and Participants

The study was a 14-week, parallel-arm, randomized clinical trial conducted between August 2018 and April 2020. Participants were adults aged 25 to 75 years with obesity and who received weight-loss treatment through the Weight Loss Medicine Clinic at the University of Alabama at Birmingham Hospital.

Interventions

All participants received weight-loss treatment (energy restriction [ER]) and were randomized to eTRE plus ER (8-hour eating window from 7:00 to 15:00) or control eating (CON) plus ER (≥12-hour window).

Main Outcomes and Measures

The co-primary outcomes were weight loss and fat loss. Secondary outcomes included blood pressure, heart rate, glucose levels, insulin levels, and plasma lipid levels.

Results

Ninety participants were enrolled (mean [SD] body mass index, 39.6 [6.7]; age, 43 [11] years; 72 [80%] female). The eTRE+ER group adhered 6.0 (0.8) days per week. The eTRE+ER intervention was more effective for losing weight (-2.3 kg; 95% CI, -3.7 to -0.9 kg; P = .002) but did not affect body fat (-1.4 kg; 95% CI, -2.9 to 0.2 kg; P = .09) or the ratio of fat loss to weight loss (-4.2%; 95% CI, -14.9 to 6.5%; P = .43). The effects of eTRE+ER were equivalent to reducing calorie intake by an additional 214 kcal/d. The eTRE+ER intervention also improved diastolic blood pressure (-4 mm Hg; 95% CI, -8 to 0 mm Hg; P = .04) and mood disturbances, including fatigue-inertia, vigor-activity, and depression-dejection. All other cardiometabolic risk factors, food intake, physical activity, and sleep outcomes were similar between groups. In a secondary analysis of 59 completers, eTRE+ER was also more effective for losing body fat and trunk fat than CON+ER.

Conclusions and Relevance

In this randomized clinical trial, eTRE was more effective for losing weight and improving diastolic blood pressure and mood than eating over a window of 12 or more hours at 14 weeks.

Trial Registration

ClinicalTrials.gov Identifier: NCT03459703.

Bibliometric and visual analysis of time-restricted eating

An increasing number of studies have shown the effects of time-restricted eating (TRE) on metabolic diseases and cardiovascular diseases associated with obesity. However, no bibliometric analyses were conducted in this field systematically. In our study, we aimed to visualize the publications about TRE to determine the frontiers and hotspots and then provide references and guidance for further studies. Publications about TRE were exported from the Web of Science Core Collection (WOSCC) database. VOSviewer 1.6.16 was adopted to perform the bibliometric analysis. In our study, a total of 414 publications with 298 articles and 116 reviews were included. The publications in this field showed an upward trend from 2016. A total of 2016 authors contributed to this field. The most productive authors were Satchidananda Panda, Krista A Varady and Emily NC Manoogian. All publications were distributed from about 624 organizations from 49 Countries/Regions. The leading institutions were the Salk Institute for Biological Studies, the University of California San Diego and the University of Alabama at Birmingham, and the most productive countries were the United States, the People’s Republic of China and Japan. All publications were from 182 journals, and the most productive journals were Nutrients, Frontiers in Nutrition and Cell Metabolism. The first highest cited reference with 991 citations was published in Cell Metabolism, and authored by Satchidananda Panda et al. There were four indicating research directions, and the keywords of the green cluster were time-restricted feeding, metabolism, circadian clock, and circadian rhythm. The keywords of the blue cluster were obesity, health, diet, and food intake. The keywords of the red cluster were intermittent fasting, weight loss, caloric restriction, and time-restricted eating. The keywords of the yellow cluster were insulin resistance, metabolic disease, cardiovascular disease, and caloric intake. The main research hotspots in the TRE field were TRE and circadian rhythm, TRE and obesity, TRE and metabolic disease, and TRE and cardiovascular disease. TRE represents new directions to evaluate the effects of the timing of eating on different diseases, especially obesity, Type 2 diabetes mellitus and cardiovascular disease. Previous studies have generated impressive data on the effects of TRE on metabolic diseases and cardiovascular diseases associated with obesity. More high-quality studies are needed to assess the mechanism and efficacy of TRE in a wide range of populations and diseases.

Effects of Fasting and Lifestyle Modification in Patients with Metabolic Syndrome: A Randomized Controlled Trial

BACKGROUND

Lifestyle interventions, such as fasting, diet, and exercise, are increasingly used as a treatment option for patients with metabolic syndrome (MS). This study assesses the efficacy and safety of fasting followed by lifestyle modification in patients with MS compared to lifestyle modification only.

METHODS

Single-blind, multicenter, parallel, randomized controlled trial in two German tertiary referral hospitals in metropolitan areas.

INTERVENTIONS

(a) 5-day fasting followed by 10 weeks of lifestyle modification (modified DASH diet, exercise, mindfulness; n = 73); (b) 10 weeks of lifestyle modification only (n = 72).

MAIN OUTCOMES AND MEASURES

Co-primary outcomes were ambulatory systolic blood pressure and the homeostasis model assessment (HOMA) index at week 12. Further outcomes included anthropometric, laboratory parameters, and the PROCAM score at weeks 1, 12, and 24.

RESULTS

A total of 145 patients with metabolic syndrome (62.8% women; 59.7 ± 9.3 years) were included. No significant group differences occurred for the co-primary outcomes at week 12. However, compared to lifestyle modification only, fasting significantly reduced HOMA index (Δ = -0.8; 95% confidence interval [CI] = -1.7, -0.1), diastolic blood pressure (Δ = -4.8; 95% CI = -5.5, -4.1), BMI (Δ = -1.7; 95% CI = -2.0, -1.4), weight (Δ = -1.7; 95% CI = -2.0, -1.4), waist circumference (Δ = -2.6; 95% CI = -5.0, -0.2), glucose (Δ = -10.3; 95% CI = -19.0, -1.6), insulin (Δ = -2.9; 95% CI = -5.3, -0.4), HbA1c (Δ = -0.2; 95% CI = -0.4, -0.05;), triglycerides (Δ = -48.9; 95% CI = -81.0, -16.9), IL-6 (Δ = -1.2; 95% CI = -2.5, -0.005), and the 10-year risk of acute coronary events (Δ = -4.9; 95% CI = -9.5, -0.4) after week 1. Fasting increased uric acid levels (Δ = 1.0; 95% CI = 0.1, 1.9) and slightly reduced eGRF (Δ = -11.9; 95% CI = -21.8, -2.0). Group differences at week 24 were found for weight (Δ = -2, 7; 95% CI = -4.8, -0.5), BMI (Δ = -1.0; 95% CI = -1.8, -0.3), glucose (Δ = -7.7; 95% CI = -13.5, -1.8), HDL (Δ = 5.1; 95% CI = 1.5, 8.8), and CRP (Δ = 0.2; 95% CI = 0.03, 0.4). No serious adverse events occurred.

CONCLUSIONS

A beneficial effect at week 24 was found on weight; fasting also induced various positive short-term effects in patients with MS. Fasting can thus be considered a treatment for initializing lifestyle modification for this patient group; however, it remains to be investigated whether and how the multilayered effects of fasting can be maintained in the medium and longer term.

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.

Meal timing across the day modulates daily energy intake in adult patients with type 2 diabetes

BACKGROUND/OBJECTIVES

We assessed the association between the timing of meals across the day with diet composition and metabolic parameters in patients with type-2 diabetes (T2D).

SUBJECTS/METHODS

Eighty adults (55.2 ± 6.8 years, 45% males) patients with T2D (without insulin therapy) were included. Three non-consecutive dietary records assessed food intake. The onset time of each consumed meal/beverage was identified and assigned to one of three periods of the day: Period 1 (P1, 06:00-11:59 h), Period 2 (P2, 12:00-17:59 h), and Period 3 (P3, 18:00-00:30 h).

RESULTS

Energy intake in P1 was lower compared to P2 and P3 (22.8 ± 7.9%, 37.5 ± 9.6%, and 39.7 ± 9.9%, respectively, P < 0.001). The same pattern was found for both total protein and fat intake, but carbohydrate intake was similar among periods. Patients with greater daily energy intake (as % of total energy) in P3 showed increased total food consumption, total energy, protein, and fat intake (all P < 0.05). The opposite pattern was observed in patients with greater daily energy intake in P1 (all P < 0.05). Regression analysis showed that daily energy intake was significantly reduced when a higher proportion of carbohydrates was eaten in P1 (vs. P3, P < 0.04).

CONCLUSION

Increased energy intake late during the day is related to increased total food and daily energy intake in patients with T2D. A greater proportion of total carbohydrates eaten early during the day relates to lower total energy intake. Our results suggest that earlier food intake may be a nutritional tool for dietary and metabolic control in these patients.