Eight-hour time-restricted eating does not lower daily myofibrillar protein synthesis rates: A randomized control trial

Efficacy of time restricted eating and resistance training on body composition and mood profiles among young adults with overweight/obesity: a randomized controlled trial

BACKGROUND/OBJECTIVE

Dietary restriction or exercise regimens can promote weight loss or physical fitness among patients with obesity. However, intervention-associated adverse effects may impede patients' motivation to participate in dietary/exercise interventions. We examined the effects of time restricted eating (TRE) with or without resistance training (RT) on body composition, mood profile, and sleep quality in young college adults with overweight or obesity.

METHODS

Fifty-four young college students with overweight/obesity were randomized into control (CON), TRE, RT, and TRE plus RT (TRE+RT) trials. The TRE trials restricted to an eating window of 10-hour/day for 8-week. The RT trials performed supervised resistance exercise, while the control trial maintained a regular lifestyle. Changes in body composition variables, blood pressure, mood status, and sleep quality were measured before and after the intervention.

RESULTS

TRE intervention alone or in combination with RT significantly (p < 0.01) decreased body weight (>2 kg) and BMI (~1 kg/m2) in adults with overweight/obesity. Both RT alone and combined with TRE substantially decreased fat mass by 1.1 ± 0.5 and 3.2 ± 0.4 kg, respectively. The decreased fat mass was greater in the combination trial than in the RT trial, whereas TRE alone had no effect. In contrast, fat-free mass was significantly (p < 0.01) decreased with TRE (-2.3 ± 06 kg), increased with RT (1.6 ± 0.3 kg), and was stably maintained with combination interventions. The reduced waist and hip circumferences in the TRE (p < 0.01) were similar to those in the TRE+RT trials, however, RT alone had no effect. Time and group interaction showed a large effect size (partial eta squared) for all body composition variables. In addition, RT with or without TRE notably decreased diastolic blood pressure (RT: -5.5 ± 1.9 mmHg, TRE+RT: -4.1 ± 1.5 mmHg, p < 0.05). Mild anxiety levels at baseline in RT (4.8 ± 2.6) and TRE+RT (4.1 ± 3) trials were found to be normal at postintervention in TRE+RT (3.6 ± 1.7) but not in RT (5.6 ± 3.5). No depression or stress was recorded among the participants during the intervention. The reported poor sleep quality among participants at baseline was significantly improved with RT (4.8 ± 2.9; p < 0.05), and tended to improve with TRE+RT interventions (4.5 ± 1.9).

CONCLUSIONS

10-hour TRE is beneficial for weight/fat loss without affecting mood status. However, TRE combined with RT might be more effective for weight/fat loss, maintaining muscle mass, and good quality of sleep among young adults with overweight or obesity.

Calorie counting vs. minute counting; does nutrient timing matter for weight-loss?

PURPOSE OF REVIEW

To critically evaluate the latest evidence on the weight-loss effects of chrono-nutrition, culminating in identification of remaining gaps in the literature and future recommendations.

RECENT FINDINGS

There appear to be six articles on this topic published over the past 2 years that have ostensibly examined the weight-loss effects of chrono-nutrition strategies relative to comparator conditions involving standard eating patterns in which meal timing is not manipulated. Some of those studies have concluded that TRE may be superior to standard energy restriction for weight-loss but the data presented do not consistently support that inference.

SUMMARY

Chrono-nutrition strategies remain a popular dietary approach to weight-loss and yet there is a paucity of primary data showing that these strategies are more effective than any other means of eliciting a negative energy balance but without altering daily eating patterns.

Effect of 3 Different Daily Protein Intakes in a 2-Meal Eating Pattern on Protein Turnover in Middle Age and Older Adults: A Randomized Controlled Trial

BACKGROUND

Reduced meal frequency patterns have become popular for weight loss, maintenance, and improving cardiometabolic health. The extended fasting windows with these dietary patterns could lead to greater protein breakdown, which is a concern for middle-aged and older adults who may need higher protein intakes to maintain or increase net protein balance.

OBJECTIVES

This study aimed to quantify muscle and whole-body protein kinetic responses to 3 different daily protein intakes within a 2-meal eating pattern.

METHODS

Thirty participants (age: 61 ± 6 y, BMI: 26.5 ± 4.8 kg/m2) participated in this 24-h metabolic study using oral stable isotope tracer techniques and were randomized to 1 of 3 protein intakes: 1) recommended dietary allowance (RDA): 0.8 g/kg/d; 2) habitual United States intake: 1.1 g/kg/d; or 3) ≈2RDA: 1.5 g/kg/d distributed across 2 meals, consumed within a 9-h window.

RESULTS

Whole-body net protein balance was significantly higher for 1.5 g/kg/d compared with 0.8 g/kg/d [mean difference: 0.55 g/kg; lean body mass (LBM)/d; 95% confidence interval (CI): 0.17, 0.93 g/kg LBM/d; P = 0.004] and 1.1 g/kg/d (mean difference: 0.6 g/kg LBM/d; 95%CI: 0.23, 0.97 g/kg LBM/d; P = 0.001), with no difference between 0.8 and 1.1 g/kg/d (mean difference: 0.05 g/kg LBM/d; 95%CI: -0.31, 0.40 g/kg LBM/d; P = 0.936). Muscle protein synthesis was not significantly different between any groups (P = 0.388).

CONCLUSION

s: Within a 2-meal eating pattern, a protein intake of 1.5 g/kg/d led to a more positive whole-body net protein balance than intakes of 0.8 and 1.1 g/kg/d in middle-aged and older adults. This trial was registered at clinicaltrials.gov as NCT04830514.

Systematic Review and Meta-analysis of Randomized Clinical Trials Comparing Time-Restricted Eating With and Without Caloric Restriction for Weight Loss

CONTEXT

Although it is well established that caloric restriction (CR) is the primary driver of weight loss, circadian-driven metabolic benefits have been recognized as possibly enhancing the effects of CR. Time-restricted eating (TRE) has emerged as a promising approach in this context.

OBJECTIVE

We conducted a systematic review and meta-analysis to compare the effects of TRE with isocaloric diet controls (analysis 1) and non-isocaloric controls (analysis 2) on anthropometric and body-composition parameters in adults with overweight or obesity.

DATA SOURCES

A search was carried out in the Medline, LILACS, Embase, and CENTRAL databases using Medical Subject Heading (MeSH) and similar terms such as "Obesity," "Obesity, Abdominal," "Time-restricted eating," "Body weight," "Changes in body weight," and others.

DATA EXTRACTION

We included 30 studies involving a total of 1341 participants. Studies were screened based on titles and abstracts followed by full-text reading, and data were extracted from eligible studies using a pre-established form. All these steps were performed by 2 authors independently and blinded, with discrepancies resolved by a third author.

DATA ANALYSIS

The results of main findings revealed that, in studies using non-isocaloric controls, the TRE group showed significant reductions in body weight (BW) (mean difference [MD]: -2.82 kg; 95% CI: -3.49, -2.15), fat mass (FM) (MD: -1.36 kg; 95% CI: -2.09, -0.63), and fat-free mass (FFM) (MD: -0.86 kg; 95% CI: -1.23, -0.49). In studies that used isocaloric control strategies, the TRE group showed significant reductions in BW (MD: -1.46 kg; 95% CI: -2.65, -0.26), FM (MD: -1.50 kg; 95% CI: -2.77, -0.24), and FFM (MD: -0.41 kg; 95% CI: -0.79, -0. 03).

CONCLUSION

TRE yields favorable anthropometric and clinical outcomes, even when intake is isocaloric between the intervention and control groups. This result suggests that circadian effects may enhance the impact of CR on excess weight.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022301594.

Early Time-Restricted Eating Improves Weight Loss While Preserving Muscle: An 8-Week Trial in Young Women

Background: Time-restricted eating (TRE) has gained attention as a novel dietary intervention that restricts the daily eating window, potentially offering improved metabolic health and body composition. Nevertheless, whether early TRE (eTRE) or delayed TRE (dTRE) best enhances resistance training (RT) adaptations remains unclear. Methods: In this 8-week randomized study, 24 healthy young women with limited RT experience were assigned into one of three groups: eTRE (an 8:00 AM-2:00 PM feeding window), dTRE (12:00 PM-6:00 PM), or the control (8:00 AM-8:00 PM). Apart from the timing restrictions, no further dietary guidance was provided. All of the participants performed standardized knee-supported push-ups (4 sets × 10 reps, three sessions/week). The primary outcomes included body weight, the thickness of the triceps brachii long head (measured via ultrasound), and push-up endurance. Results: The eTRE group achieved a significant reduction in body weight (-2.61 ± 1.06 kg; p < 0.001), which surpassed the changes observed in both the dTRE (-1.44 ± 1.12 kg) and control (-0.48 ± 0.64 kg) groups. However, no significant between-group differences emerged for muscle thickness or push-up performance. All groups showed comparable improvements in triceps brachii thickness (a 1.36-1.55 mm increase) and push-up endurance (62-74 additional repetitions). Conclusions: Early TRE (8:00 AM-2:00 PM) appears to be more beneficial than delayed TRE (12:00 PM-6:00 PM) for weight management when combined with RT, yet both TRE regimens result in similar improvements in muscle thickness and endurance. These findings suggest that optimizing meal timing in alignment with circadian rhythms may enhance weight control without hindering muscle adaptations, providing a practical approach for individuals seeking to lose weight while preserving or increasing their muscular fitness. Future research involving larger samples and diverse populations is warranted to confirm these results and clarify the underlying metabolic mechanisms.

Time Restricted Eating: A Valuable Alternative to Calorie Restriction for Addressing Obesity?

PURPOSE OF REVIEW

In this review, we summarize the molecular effects of time-restricted eating (TRE) and its possible role in appetite regulation. We also discuss the potential clinical benefits of TRE in obesity.

RECENT FINDINGS

TRE is an emerging dietary approach consisting in limiting food intake to a specific window of time each day. The rationale behind this strategy is to restore the circadian misalignment, commonly seen in obesity. Preclinical studies have shown that restricting food intake only during the active phase of the day can positively influence several cellular functions including senescence, mitochondrial activity, inflammation, autophagy and nutrients' sensing pathways. Furthermore, TRE may play a role by modulating appetite and satiety hormones, though further research is needed to clarify its exact mechanisms. Clinical trials involving patients with obesity or type 2 diabetes suggest that TRE can be effective for weight loss, but its broader effects on improving other clinical outcomes, such as cardiovascular risk factors, remain less certain. The epidemic proportions of obesity cause urgency to find dietary, pharmacological and surgical interventions that can be effective in the medium and long term. According to its molecular effects, TRE can be an interesting alternative to caloric restriction in the treatment of obesity, but the considerable variability across clinical trials regarding population, intervention, and follow-up duration makes it difficult to reach definitive conclusions.

Physiological rhythms and metabolic regulation: Shining light on skeletal muscle

Metabolic regulation is essential for maintaining homeostasis in response to fluctuating dietary nutrient availability. In this review, we explore how metabolic health can be affected by the temporal alignment between daily behavioural patterns (e.g., eating, physical activity and sleep) and recurring cycles in underlying physiology (e.g., 'circadian' rhythms). Misalignment within and/or between these patterns and cycles can lead to metabolic dysregulation, increasing the risk of chronic disease states such as obesity, type 2 diabetes and cardiovascular disease. Conversely, metabolic health can be improved by strategically aligning certain behavioural patterns with endogenous rhythms in physiology. Dietary interventions based upon this reasoning are referred to as chrono-nutrition strategies. Skeletal muscle is an important tissue in relation to both whole-body metabolism and behaviour and plays a central role in how physiological rhythms respond to the timing of nutrient delivery/availability. Few studies have examined rhythms in metabolism within human skeletal muscle, providing opportunities to advance current understanding of how nutrient timing affects muscle metabolism.

The Impact of Breakfast Consumption or Omission on Exercise Performance and Adaptations: A Narrative Review

BACKGROUND

Breakfast is often termed the most important meal of the day. However, its importance to acute and chronic adaptations to exercise is currently not well summarized throughout the literature.

METHODS

A narrative review of the experimental literature regarding breakfast consumption's impact on acute and chronic exercise performance and alterations in body composition prior to November 2024 was conducted. To be included in this review, the selected investigations needed to include some aspect of either endurance or resistance training performance and be conducted in humans.

RESULTS

These findings suggest that breakfast consumption may benefit acute long-duration (>60 min) but not short-duration (<60 min) morning endurance exercise. Evening time trial performance was consistently inhibited following breakfast omission despite the resumption of eating midday. No or minimal impact of breakfast consumption was found when examining acute morning or afternoon resistance training or the longitudinal adaptations to either resistance or endurance training. Favorable changes in body composition were often noted following the omission of breakfast. However, this was primarily driven by the concomitant reduced kilocalorie intake.

CONCLUSIONS

Consuming breakfast may aid endurance athletes regularly performing exercise lasting >60 min in length. However, the morning meal's impact on resistance training and changes in body composition appears to be minimal. Although, as the body of literature is limited, future investigations are needed to truly ascertain the dietary practice's impact.

Short-term intermittent fasting and energy restriction do not impair rates of muscle protein synthesis: A randomised, controlled dietary intervention

BACKGROUND

Intermittent fasting (IF) is an effective energy restricted dietary strategy to reduce body and fat mass and improve metabolic health in individuals with either an overweight or obese status. However, dietary energy restriction may impair muscle protein synthesis (MPS) resulting in a concomitant decline in lean body mass. Due to periods of prolonged fasting combined with irregular meal intake, we hypothesised that IF would reduce rates of MPS compared to an energy balanced diet with regular meal patterns.

AIMS

We assessed the impact of a short-term, ten days, alternate day fasting or a continuous energy restricted diet to a control diet on integrated rates of skeletal MPS in middle-aged males with overweight or obesity.

METHODS

Twenty-seven middle-aged males with overweight or obesity (age: 44.6 ± 5.4 y; BMI: 30.3 ± 2.6 kg/m2) consumed a three-day lead-in diet, followed by a ten-day controlled dietary intervention matched for protein intake, as alternate day fasting (ADF: 62.5 energy (En)%, days of 25 En% alternated with days of 100 En% food ingestion), continuous energy restriction (CER: 62.5 En%), or an energy balanced, control diet (CON: 100 En%). Deuterated water (D2O) methodology with saliva, blood, and skeletal muscle sampling were used to assess integrated rates of MPS over the ten-day intervention period. Secondary measures included fasting plasma glucose, insulin, and gastrointestinal hormone concentrations, continuous glucose monitoring, and assessment of body composition.

RESULTS

There were no differences in daily rates of MPS between groups (ADF: 1.18 ± 0.13, CER: 1.13 ± 0.16, and CON: 1.18 ± 0.18 %/day, P > 0.05). The reductions in body mass were greater in ADF and CER compared to CON (P < 0.001). Lean and fat mass were decreased by a similar magnitude across groups (main time effect, P < 0.001; main group effect, P > 0.05). Fasting plasma leptin concentrations decreased in ADF and CER (P < 0.001), with no differences in fasting plasma glucose or insulin concentrations between groups.

CONCLUSION

Short-term alternate day fasting does not lower rates of MPS compared to continuous energy restriction or an energy balanced, control diet with matched protein intake. The prolonged effects of IF and periods of irregular energy and protein intake patterns on muscle mass maintenance remain to be investigated. This trial was registered under Australian New Zealand Clinical Trial Registry (https://www.anzctr.org.au), identifier no. ACTRN12619000757112.

Synergistic Effects of Time-Restricted Feeding and Resistance Training on Body Composition and Metabolic Health: A Systematic Review and Meta-Analysis

BACKGROUND

This systematic review and meta-analysis examined the synergistic impact of time-restricted feeding (TRF) combined with resistance training (RT) (TRF + RT) on body composition and metabolic health in adults, contrasting it with habitual eating patterns (CON) and RT (CON + RT).

METHODS

Adhering to PRISMA guidelines, five databases were searched up to 28 April 2024. Randomized controlled trials or crossover trials assessing the effects of TRF + RT for at least 4 weeks in adults were selected. Data were pooled as standardized mean differences (SMDs) or weighted mean differences (WMDs) with 95% confidence intervals (CIs). The risk of bias was evaluated using the revised Cochrane risk-of-bias tool.

RESULTS

Seven studies with 164 participants were included in the final analysis. TRF + RT significantly reduced body mass (WMD -2.90, 95% CI: -5.30 to -0.51), fat mass (WMD -1.52, 95% CI: -2.30 to -0.75), insulin (SMD -0.72, 95% CI: -1.24 to -0.21), total cholesterol (WMD -9.44, 95% CI: -13.62 to -5.27), low-density lipoprotein cholesterol (LDL-C) (WMD -9.94, 95% CI: -13.47 to -6.41), and energy intake (WMD -174.88, 95% CI: -283.79 to -65.97) compared to CON + RT. No significant changes were observed in muscle mass, strength, or other metabolic markers.

CONCLUSIONS

TRF + RT, in contrast to CON + RT, significantly improved body composition, insulin, and cholesterol levels without affecting muscle mass or strength.

Time-Restricted Eating and Bone Health: A Systematic Review with Meta-Analysis

Time-restricted eating (TRE) has emerged as a dietary strategy that restricts food consumption to a specific time window and is commonly applied to facilitate weight loss. The benefits of TRE on adipose tissue have been evidenced in human trials and animal models; however, its impact on bone tissue remains unclear. To systematically synthesize and examine the evidence on the impact of TRE on bone health (bone mineral content (BMC), bone mineral density (BMD), and bone turnover factors), PubMed, Scopus, Cochrane CENTRAL, and Web of Science databases were systematically explored from inception to 1 October 2023 searching for randomized controlled trials (RCTs) aimed at determining the effects of TRE on bone health in adults (≥18 years). The Cochrane Handbook and the PRISMA recommendations were followed. A total of seven RCTs involving 313 participants (19 to 68 years) were included, with an average length of 10.5 weeks (range: 4 to 24 weeks). Despite the significant weight loss reported in five out of seven studies when compared to the control, our meta-analysis showed no significant difference in BMD (g/cm2) between groups (MD = -0.009, 95% CI: -0.026 to 0.009, p = 0.328; I2 = 0%). BMC and bone turnover markers between TRE interventions and control conditions were not meta-analyzed because of scarcity of studies (less than five). Despite its short-term benefits on cardiometabolic health, TRE did not show detrimental effects on bone health outcomes compared to those in the control group. Nevertheless, caution should be taken when interpreting our results due to the scarcity of RCTs adequately powered to assess changes in bone outcomes.

The effect of time of eating on cardiometabolic risk in primary and secondary prevention of cardiovascular disease

Continuous energy restriction is currently considered the first-line dietary therapy for weight loss in individuals with obesity. Recently, interventions which alter the eating window and time of eating occasions have been explored as means to achieve weight loss and other cardiometabolic improvements such as a reduction in blood pressure, glycaemia, lipids and inflammation. It is unknown, however, whether these changes result from unintentional energy restriction or from other mechanisms such as the alignment of nutrient intake with the internal circadian clock. Even less is known regarding the safety and efficacy of these interventions in individuals with established chronic noncommunicable disease states, such as cardiovascular disease. This review examines the effects of interventions which alter both eating window and time of eating occasions on weight and other cardiometabolic risk factors in both healthy participants and those with established cardiovascular disease. We then summarise the state of existing knowledge and explore future directions of study.

Does early time-restricted eating reduce body weight and preserve fat-free mass in adults? A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis evaluated whether weight loss caused by early time-restricted eating could promote fat mass loss while preserving fat-free mass, thereby leading to improvements in inflammation and metabolic health.

METHODS

Relevant randomized controlled trials (RCTs) published up to March 28, 2023, were identified in six databases, including PubMed, Web of Science, and Embase.

RESULTS

We initially screened 1279 articles, thirteen RCTs with 859 patients were ultimately included. Compared with nontime-restricted eating, early time-restricted eating significantly reduced body weight (-1.84 kg [-2.28, -1.41]; I2 = 56 %; P < 0.00001), fat mass (-1.10 kg [-1.47, -0.74]; I2 = 42 %; P < 0.00001), waist circumstance (-3.21 cm [-3.90, -2.51]; I2 = 43 %; P < 0.00001), visceral fat area (-9.76 cm2 [-13.76, -5.75]; I2 = 2 %; P < 0.00001), and inflammation as measured by tumour necrosis factor-α (-1.36 pg/mL [-2.12, -0.60]; I2 = 42 %; P < 0.001). However, early time-restricted eating did not lead to a significant change in fat-free mass (-0.56 kg [-1.16, 0.03]; I2 = 59 %; P = 0.06). Subgroup analysis showed that the early time-restricted eating of the 16:08 (fasting-time versus eating-time) strategy had a superior effect on preserving fat-free mass (-0.25 kg [-0.68, 0.18]; I2 = 0 %; P = 0.25) while significantly reducing body weight (-1.60 kg [-2.09, -1.11]; I2 = 0 %; P < 0.001) and improving metabolic outcomes.

CONCLUSIONS

Early time-restricted eating, especially 16:08 strategy, appears to be an effective strategy to decrease body weight, fat mass, abdominal obesity and inflammation, but less likely to decrease fat-free mass.

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.