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TOPLINE:

Among young adults with overweight or obesity, 8 weeks of 6-hour early or late time-restricted eating (TRE) altered gut microbiota composition and serum metabolite profiles, and the changes were significantly associated with weight loss and improvements in cardiometabolic health.

METHODOLOGY:

• TRE, an intermittent fasting approach, is emerging as an alternative dietary intervention easier to adhere to than calorie restriction, but whether early vs late eating windows differentially affect the composition of gut microbiota, serum metabolites, and cardiometabolic outcomes remain unclear.
• Researchers performed a secondary analysis of an 8-week randomized controlled trial conducted in China between October and December 2020 to evaluate the effects of early and late TRE on gut microbiome composition and serum metabolic profiles among young adults with overweight or obesity.
• A total of 60 young adults with overweight or obesity (mean age, 22.1- 23.8 years; BMI ≥ 24) who completed the trial and provided 120 fecal and blood samples were included in the final analysis. Participants were randomly assigned to the 6-hour early TRE (7 AM to 1 PM), 6-hour late TRE (12 PM to 6 PM), or the ad libitum control group.
• The composition of gut microbiota was characterized using 16S ribosomal RNA sequencing, and serum metabolomics was quantified using ultra-high-performance liquid chromatography-tandem mass spectrometry.

TAKEAWAY:

• After 8 weeks, participants in the 6-hour early TRE group reduced calorie intake by approximately 554.1 kcal, carbohydrates by 80.9 g, and protein by 20.9 g, while the 6-hour late TRE group reduced calorie intake by 407 kcal and fat intake by 20 g compared with the control group.
• Both the early TRE and late TRE groups significantly increased gut microbial alpha-diversity compared with the control group (P < .05).
• Compared with the control group, the early TRE group had a higher abundance of Faecalibacterium and Lactobacillus and a lower abundance of unclassified f_Ruminococcaceae and unclassified f_Peptostreptococcaceae. The late TRE group had an increased abundance of Faecalibacterium and unclassified f_Lachnospiraceae but a decreased abundance of Shigella and unclassified f_Peptostreptococcaceae (all false discovery rate-adjusted P < .05).
• Differential serum metabolite profiles revealed distinct biologic signatures by eating window timing, including L-malic acid with (control vs early TRE), isovaleric acid and oleic acid (control vs late TRE), and L-malic acid and pyroglutamic acid (early TRE vs late TRE).
• Changes in specific gut taxa correlated with distinct shifts in serum metabolites, and these microbe — metabolite signatures were associated with cardiometabolic improvements — reduced waist and hip circumferences, lowered systolic blood pressure, and improved insulin -related measures.

IN PRACTICE:

“Our study provides valuable insights into the relationship between time-restricted eating, gut microbiota, and serum metabolites in adults with overweight or obesity. This knowledge can assist young adults with overweight and obesity in making more informed decisions when selecting dietary approaches to reduce weight and improve cardiometabolic health,” the authors wrote. 

SOURCE:

The study, led by Li-Min Zhang, Hebei Medical University in Shijiazhuang, China, was published online in Obesity.

LIMITATIONS:

The study was limited to traditional 16S rRNA-based microbiome analysis, which failed to achieve strain-level resolution. The 6-hour TRE intervention produced unintentional reductions in energy intake, making it unclear whether the observed changes in gut microbiome and serum metabolome were attributable to caloric restriction, the extended fasting period alone, or both. The restrictive 6-hour eating window may have limited the feasibility of long-term adherence. The sample size may have limited statistical power and amplified individual variability.

DISCLOSURES:

The study was funded by the Science Research Project of the Hebei Education Department, the Natural Science Foundation of Hebei Province, and the Postdoctoral Fund of Hebei Medical University. The authors declared having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.