Effect of 8-Hour Time-Restricted Eating (16/8 TRE) on Glucose Metabolism and Lipid Profile in Adults: A Systematic Review and Meta-Analysis

CONTEXT: A dietary regimen that includes a fasting period of 16 hours coupled with a daily time-restricted eating (TRE) period of 8 hours (16/8 TRE) is gaining popularity; however, its effect on glycolipid metabolic markers remains unclear.

OBJECTIVE: In this systematic review and meta-analysis of reported studies we aimed to examine the effects on glycolipid metabolism of the 16/8 TRE dietary regimen compared with a control diet in adult study participants.

DATA SOURCES: We searched the PubMed, MEDLINE, Cochrane Library, Scopus, and Web of Science databases for relevant articles published from database inception until January 15, 2025.

DATA EXTRACTION: We extracted publication details, including data on study participant characteristics, intervention durations, and outcomes.

DATA ANALYSIS: All analyses were conducted using a random-effects model with the standardized mean difference (SMD). Subgroup analyses were performed for physical activity (PA) level, participant sex, and intervention duration.

RESULTS: In total, 23 randomized controlled trials (RCTs)with a total of 1280 participants were included in this analysis. The 16/8 TRE intervention resulted in a slight reduction in levels of fasting glucose (SMD, -0.25; 95% CI, -0.42 to -0.08; P = .004), homeostasis model assessment for insulin resistance (HOMA-IR) (SMD, -0.16; 95% CI, -0.29 to -0.02; P = .03), and insulin levels (SMD, -0.22; 95% CI, -0.43 to -0.01; P = .04). Regarding lipid profiles, 16/8 TRE had a modest effect on high-density lipoprotein cholesterol (HDL-C) (SMD, 0.15; 95% CI: 0.01-0.29; P = .04). No significant effects were found for other markers compared to the control diet. Subgroup analysis suggested the presence of sex differences in triglycerides (TGs) and low-density lipoprotein cholesterol (LDL-C), with significant improvements in TGs (SMD, -0.52; 95% CI, -1.04 to -0.01; P = .05), and LDL-C (SMD, -0.41; 95% CI, -0.75 to -0.07; P = .02) found in studies with only male participants. Additionally, participants with higher PA levels demonstrated greater improvements in LDL-C (SMD, -0.43; 95% CI, -0.74 to -0.12; P = .007). Studies with durations exceeding 6 months showed a significant improvement in HbA1c (SMD, -0.31; 95% CI, -0.56 to -0.05; P = .02).

CONCLUSION: Study participants who followed the 16/8 TRE showed an overall improvement in fasting glucose, HOMA-IR, insulin, and HDL-C levels compared to participants who followed the control diet. However, the effects of the 16/8 TRE in individuals were likely to have been moderated by participant sex, PA level, and intervention duration.

SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration No. CRD42025645789.