Diet quality is associated with measures of body fat in adolescents from Otago, New Zealand.

OBJECTIVE To examine the potential associations between diet quality and multiple measures of body composition in a sample of New Zealand adolescents aged 14-18 years. DESIGN Cross-sectional survey of eleven high schools in Otago, New Zealand. Each participant completed an online FFQ and a New Zealand Diet Quality Index for Adolescents (NZDQI-A) score was calculated based on variety and adequacy of intake for five major food groups. Besides height and waist circumference measurements, body composition was assessed using segmental bio-impedance analysis. Generalized estimating equations were used to examine associations between diet quality and body composition in models adjusted for sex, age, ethnicity and socio-economic status. SETTING High schools in Otago, New Zealand. SUBJECTS High-school students (n 681, 56 % male, mean age 16·1 (sd 1·5) years) participating in the Otago School Students Lifestyle Survey Two. RESULTS Higher NZDQI-A scores were significantly associated with lower body fat percentage (β=-0·19; 95 % CI -0·35, -0·04; P=0·014), fat-to-lean mass ratio (β=-0·26; 95 % CI -0·46, -0·05; P=0·016) and lower fat mass index (β=-0·23; 95 % CI -0·45, -0·004; P=0·046) after multivariate adjustment. No association was found between NZDQI-A and BMI, waist circumference or waist-to-height ratio. CONCLUSIONS Diet quality, as measured by NZDQI-A, was associated only with measures of body fat, not measures of overall body size. Measures specific to body fat should be used for more accurate ascertainment of body composition in examining the diet-body composition associations in this age group.