Relationship between obesity and the triglyceride–glucose index in adults: A systematic review

Introduction: The Triglyceride–Glucose Index (TyG) is an indicator with potentially high reliability in the measurement of metabolic risk in adults with obesity, therefore, the objective of the study was to analyze the relationship between obesity and the TyG in adults. Methods: A systematic review was conducted following the PRISMA 2020 guidelines, with the protocol registered in PROSPERO (CRD420251134791). Searches were performed in PubMed, Scopus, and Web of Science (Core Collection) for studies published from January 2020 to July 2025 in English and Spanish, using MeSH-based terms: (“obesity” OR “overweight” OR “abdominal obesity” OR “visceral adiposity”) AND (“triglyceride–glucose index” OR “TyG index” OR “TyG”). Methodological quality was evaluated with the Newcastle–Ottawa Scale (NOS) and evidence certainty with GRADE. Results: Fourteen observational studies (n = 115,458 participants; 78.6% Asia, 14.3% Americas, 7.1% Europe) were included. Reported TyG cut-offs for identifying obesity ranged from 8.7 to 9.1, and higher TyG values were consistently associated with greater odds of obesity (OR/HR 1.7–4.3, 95% CI where available). Discriminatory capacity was moderate-to-high (AUC 0.77–0.92). TyG-derived indices (TyG-BMI, TyG-WC, TyG-WWI) further improved predictive accuracy. Across outcomes, certainty of evidence ranged from low to moderate due to heterogeneity and observational designs. Conclusions: The TyG index is a valid and consistent marker of insulin resistance and adiposity, strongly associated with general, abdominal, and sarcopenic obesity. Its simplicity and low cost support its use for early screening and metabolic risk stratification in clinical and public health settings. Keywords: Obesity, Triglyceride-glucose index, Insulin resistance, Metabolic syndrome, Systematic review. Protocol publication: PROSPERO (CRD420251134791)