OBJECTIVES: Metabolic syndrome (MetS) is a cluster of abnormalities including abdominal obesity that increases risk for diabetes and cardiovascular disease. MetS affects ∼10% of US adolescents, but more may be at risk. The MetS severity z-score (MetS-z) is a continuous measure that may be useful for indicating MetS risk. Preventing at-risk adolescents from developing MetS may be achievable through changes in lifestyle factors such as diet and physical activity. Our objective was to evaluate the relationship of lifestyle-related factors with MetS-z in adolescents. METHODS: We performed a cross-sectional analysis of adolescents (12 to 19 y) from the National Health and Nutrition Examination Survey (NHANES) 2011–2016. MetS-z was calculated from sex- and race-specific equations developed for adolescents. Sagittal Abdominal Diameter (SAD, representing abdominal visceral fat) was obtained using NHANES standard procedures. Dietary intake was estimated via two 24-hour diet recall interviews and used to calculate the Healthy Eating Index (HEI)-2015 total (range 0–100) and component scores (range 0–10) indicating diet quality. Physical activity (PA, minutes/week of voluntary moderate or vigorous exercise) was reported by participants to trained interviewers and used to determine adherence to national PA guidelines of at least 60 min/day. Multivariable linear regression was used to evaluate the relationship of HEI scores, SAD and physical activity with MetS-z. RESULTS: Sample size was 1291 (49% female, 50% white) adolescents. Means (SEM) were: Age, 15.4 y (0.09); BMI z-score, 0.63 (0.04); MetS-z, −0.08 (0.03); SAD, 18.3 cm (0.14); and HEI score, 47.4 (0.46). Median min/week of PA was 178.5, with 30.4% of adolescents meeting PA guidelines. The final model (R(2) = 0.53) included age, SAD (β = 0.17, P
