Combined Influence of Lifestyle Risk Factors on Body Fat in Spanish Adolescents - the AVENA Study

Objective: To examine the combined influence of four lifestyle risk factors related to physical activity, television viewing, sleep duration, and meal frequency on body fat (BF) in adolescents. Method: This cross-sectional study comprised 1,310 Spanish adolescents (age 13-18.5 years). Lifestyle variables were self-reported and BE indicators (weight, height, six skinfold thicknesses, waist circumference) measured during the years 2000-2002. Lifestyle risk factors were: physically inactive, >= 3 h/day watching television, < 8 h/day sleep duration, and < 5 meals a day. The number of lifestyle risk factors was calculated for each participant, ranging from 0 to 4. Results: The number of lifestyle risk factors was positively associated with sum of six skinfolds, %BF, waist circumference, and waist-height ratio (all p < 0.001). The odds ratios (95% confidence interval) of overweight (including obesity) for groups with 1, 2, and 3-4 lifestyle risk factors compared with those with 0 were 2.86 (1.77-4.62), 3.61 (2.16-6.04), and 5.81 (3.07-10.99), respectively (p for trend < 0.001). All the observations were independent of age, gender, race, socioeconomic status, and fat free mass. Conclusion: The combined influence of four lifestyle risk factors is positively associated with BE and an approximately sixfold risk of overweight in adolescents.