Drivers of adolescent adiposity: Evidence from the Australian LOOK study

Area of Science:

• Adolescent health
• Body composition research
• Obesity drivers

Background:

• Adolescence is a critical period for body composition development.
• Understanding factors influencing body fat is crucial for public health.
• Previous research has yielded mixed results on lifestyle factors and adolescent body fat.

Purpose of the Study:

• To investigate the cross-sectional and longitudinal associations between body fat percentage (%BF) and physical activity (PA), moderate-to-vigorous PA (MVPA), sedentary time (ST), and dietary intake.
• To utilize valid and reliable measures for accurate assessment.

Main Methods:

• Longitudinal cohort study involving 556 participants initially (aged 12.4 years) and 269 at follow-up (aged 16.3 years).
• Body fat percentage (%BF) measured by dual-energy X-ray absorptiometry.
• Habitual PA, MVPA, and ST assessed via accelerometry.
• Dietary intake recorded using multi-pass 24-hour recalls.
• Statistical analysis using general linear mixed modelling, accounting for under-reporting of energy intake.

Main Results:

• Cross-sectionally, 10 minutes more MVPA/day was associated with 0.6% lower %BF, and 10 minutes less ST/day with 0.07% lower %BF, independent of PA.
• %BF was not significantly related to total energy, sugar, or fat intake.
• Longitudinally, a 3% increase in PA over 4 years was associated with a 0.08% reduction in %BF.

Conclusions:

• Body fat percentage in adolescents is independently associated with physical activity levels and sedentary time.
• Dietary intake (energy, sugar, fat) showed no significant relationship with body fat percentage in this cohort.
• Public health campaigns targeting adolescent obesity should prioritize increasing physical activity and reducing sedentary behavior over solely focusing on dietary modifications.