Review of the Association Between Neck Circumference and Multisystem Diseases: From an Anthropometric Indicator to a Clinical Risk Marker

Background: Obesity is a core risk factor for multiple chronic diseases. Adipose tissue distribution has greater predictive value for metabolic and cardiovascular risk than total fat mass. Neck circumference, a simple anthropometric indicator of upper-body subcutaneous fat accumulation, has gained increasing attention in recent years for its value in metabolic and cardiovascular risk stratification.Objective: To systematically search for and synthesize evidence on the association between neck circumference and multisystem diseases and to evaluate the evidence base and key challenges for translating neck circumference from an anthropometric indicator into a clinical risk marker.Methods: This review is a systematically searched narrative review. PubMed, Embase, Web of Science, Cochrane Library, and CNKI were searched from database inception to June 30, 2026. A supplementary search was performed for 2026 articles published online after the search cutoff date. Systematic reviews and meta-analyses of the association between neck circumference and disease or risk factors served as the primary evidence source and were supplemented by large prospective cohort studies and key cross-sectional studies. Case reports, small-sample uncontrolled studies, purely hypothetical articles, conference abstracts, preprints, and registered trial protocols were excluded. Evidence was synthesized narratively, and effect sizes were not pooled. The review was not prospectively registered, and no formal evidence grading was performed with tools such as GRADE. Related limitations are discussed in Section 9.1.Results: A total of 130 articles were included. Current evidence indicates that increased neck circumference is epidemiologically associated with type 2 diabetes mellitus (T2DM), gestational diabetes mellitus (GDM), components of metabolic syndrome (MetS), dyslipidemia, obstructive sleep apnea (OSA), polycystic ovary syndrome (PCOS), atrial fibrillation, heart failure, ischemic stroke, chronic kidney disease (CKD), hyperuricemia, gout, and the risk of cardiovascular events and all-cause mortality. Associations with left ventricular hypertrophy (LVH), cardiac electrical remodeling, subclinical atherosclerosis, arterial stiffness, retinal microvascular changes, decline in lung function, metabolic dysfunction-associated steatotic liver disease (MASLD), coronary heart disease, cognitive impairment, and reduced brain gray matter volume have also been reported, but the evidence is weaker, inconsistent in direction, or confined to subgroups. The prognosis of hemorrhagic stroke also requires further validation. The direction of associations for geriatric and nutritional outcomes such as sarcopenia, malnutrition, and decline in activities of daily living (ADL) is inconsistent, with some studies showing risk associated with lower neck circumference; presarcopenic obesity, in contrast, is positively associated with increased neck circumference. Evidence for associations with metabolic syndrome in children with type 1 diabetes mellitus, bone mineral density, depression, and sleep quality is weak, inconsistent in direction, or confined to specific subgroups. Some associations, such as those for T2DM and hypertension, remain significant after adjustment for body mass index (BMI), and the CKD evidence is partially supportive. Evidence strength was judged comprehensively based on study design, cross-population consistency, whether associations remained significant after adjustment for BMI or waist circumference, and the availability of Mendelian randomization (MR) evidence; overall, the evidence was heterogeneous. However, neck circumference is strongly collinear with waist circumference and BMI. Some meta-analyses have shown no significant association between neck circumference and the composite MetS endpoint. The Jackson Heart Study found no independent association between neck circumference and cardiovascular outcomes after full adjustment. MR studies have shown a protective causal association between neck circumference and metabolic dysfunction-associated fatty liver disease (MAFLD), contradicting observational studies; other MR studies have not found a causal association between neck circumference and bone mineral density. Wrist circumference outperforms neck circumference in predicting insulin resistance in children, and in children with type 1 diabetes mellitus, waist circumference has a higher area under the curve (AUC) than neck circumference for predicting MetS. Causality has not yet been fully established. Genetic evidence indicates that neck circumference has a genetic basis independent of overall obesity. Intervention studies suggest that neck circumference can be changed by lifestyle interventions, but its changes are not fully synchronized with improvements in neck adipose tissue or core OSA endpoints. Evidence from nontraditional cardiovascular risk markers, mechanistic studies, studies in special populations, measurement standardization studies, and evidence on local effects in head and neck cancer has further expanded the boundaries of clinical application of neck circumference. Prospective evidence in the field of nonalcoholic fatty liver disease (NAFLD) shows that in postmenopausal women with normal BMI, baseline neck circumference still independently predicts NAFLD incidence. Studies in young Chinese adults suggest that there are significant sex differences in the performance of neck circumference for diagnosing obesity.Conclusions: As a systematically searched narrative review, this review suggests that neck circumference is epidemiologically associated with multisystem diseases, but the strength of evidence is heterogeneous. Current evidence supports its use as an adjunctive indicator for risk screening; however, it cannot yet serve as an independent causal risk marker. Cross-disease comparisons of effect sizes are influenced by differences in indicator type, baseline risk, and follow-up duration and should not be used as a direct basis for clinical decision-making.