Do Physical Activity and Diet Independently Account for Variation in Body Fat in Children and Adolescents? A Systematic Review Unpacking the Roles of Exercise and Diet in Childhood Obesity.

Only four of approximately 700 publications explored satisfied all pre-set methodological standards for examining independent associations of adiposity with physical activity and energy intake in free-living children and adolescents.

• Approximately 700 publications were initially explored.
• Acceptable publications required objective measures of fat mass and physical activity, best standard practice energy intake assessments, and appropriate statistical modeling.
• Studies were restricted to free-living town or city-dwelling children and adolescents.
• All four qualifying studies involved predominantly White participants from westernized cities.

Adiposity was strongly independently and negatively related to physical activity across all four qualifying studies.

• All four studies had the same outcome regarding the physical activity-adiposity relationship.
• The relationship was described as 'strongly independently and negatively related.'
• Physical activity was measured objectively in all included studies.
• Fat mass was also measured objectively in all included studies.

There was no evidence of any independent relationship between adiposity and energy intake across all four qualifying studies.

• All four studies showed no independent association between energy intake and adiposity.
• Children with higher adiposity consumed no more food and beverage energy than their leaner counterparts.
• Energy intake assessments used best standard practice methods.
• The result was consistent across all studies meeting methodological criteria.

Post-hoc assessments were unable to find evidence that potential misreporting, particularly under-reporting by participants with greater adiposity, influenced the outcomes regarding the energy intake-adiposity relationship.

• Under-reporting by participants with greater adiposity was specifically considered as a potential confound.
• Post-hoc assessments were conducted to evaluate whether misreporting affected results.
• Despite the subjective nature of energy intake assessments, post-hoc analyses did not reveal evidence of bias altering the null finding.
• The authors acknowledged that 'inaccuracy masked relationships' remains a possibility given the subjective nature of energy intake assessments.

The authors concluded that campaigns targeting youth obesity would benefit from strategies focusing strongly on increasing physical activity.

• The conclusion was based on the consistency of outcomes across all four well-executed studies in the review.
• The authors noted 'the vital role that sound nutrition plays in the healthy development of our youth' while still prioritizing physical activity in obesity campaigns.
• Additional well-designed research was identified as needed.
• The recommendation was framed as complementary to, not replacing, nutritional guidance for healthy youth development.

The independent impacts of physical activity and energy intake on adiposity in children living in westernized environments are described as inconclusive in the existing literature due to insufficient methodological rigor in most studies.

• Few studies employed 'sufficiently robust methodology to provide solid independent associative data.'
• Physical activity and energy intake are described as 'central targets of community initiatives to reduce the prevalence of childhood obesity.'
• The review was restricted to westernized, urban-dwelling children and adolescents.
• The general effects of physical activity and energy intake on energy balance and body composition were acknowledged as clear, while independent impacts were described as 'inconclusive.'