Effects of Time-Restricted Eating on Insulin Sensitivity, Glycemic Control, and Metabolic Outcomes in Low- and Middle-Income Countries: A Systematic Review.

BACKGROUND: Metabolic disease is accelerating across Low- and Middle-Income Countries (LMICs), where calorie-focused dietary prescriptions frequently fail due to cost and complexity. Time-Restricted Eating (TRE) is a distinct approach. It restructures when food is eaten rather than what or how much, limiting daily intake to a 6 to 10 hour window as a cost-free chronomedicine strategy. Its mechanisms and long-term glycemic effects in diverse LMIC populations remain incompletely synthesised. OBJECTIVES: To systematically review TRE's clinical efficacy on glycemic control, insulin sensitivity, and anthropometric outcomes across LMIC cohorts, and to evaluate molecular evidence for AMPK/mTOR pathway activation. DATA SOURCES AND METHODS: A PRISMA 2020-compliant systematic review was conducted using PubMed, Scopus, and Web of Science. Eligible studies included randomised controlled trials and quasi-experimental designs involving adults in LMICs with metabolic conditions. TRE windows of 6 to 10 hours were required. Risk of bias was assessed using RoB 2.0 and ROBINS-I. The review was prospectively registered with PROSPERO (CRD420261352841). RESULTS: Twenty-six unique cohorts (28 reports) across India, China, Indonesia, Iran, Tunisia, and Brazil were included. TRE was associated with reductions in insulin resistance, fasting blood sugar, and body weight across most included studies. A persistent HbA1c reduction of -0.78% at 18 months in one longitudinal cohort suggested that glycemic benefits may compound with sustained adherence. Contradictions emerged between centres regarding TRE's superiority over caloric restriction. CONCLUSION: TRE may represent a feasible, low-cost dietary strategy for metabolic health management in resource-limited settings, though further evidence from larger and longer trials is needed.