P629 - MINIMUM DAYS ESTIMATION FOR RELIABLE DIETARY INTAKE INFORMATION: FINDINGS FROM A DIGITAL COHORT

P629

MINIMUM DAYS ESTIMATION FOR RELIABLE DIETARY INTAKE INFORMATION: FINDINGS FROM A DIGITAL COHORT

R. Singh^1,*, M. Verest¹, M. Salathé¹

¹School of Life Sciences, EPFL, Lausanne, Switzerland

Rationale: Daily variations in food consumption present challenges for accurate dietary intake assessment. Our study determines the minimum days needed to reliably estimate various nutrients & food groups, which could reduce user burden and study costs while maintaining data reliability.

Methods: We analyzed data from 958 participants in the Food & You digital cohort who tracked meals for at least one week using the AI-assisted MyFoodRepo app. We employed both variance ratio (CV) methods using linear mixed models and intraclass correlation coefficient (ICC) analyses for minimum days estimation and to identify optimal collection periods. Additionally, we analyzed demographic and temporal factors affecting nutritional intake patterns.

Results: Our analysis using CV and ICC methods revealed that water, coffee, and food quantity could be reliably estimated with just 1-2 days of data (r>0.85), while most macronutrients required 2-3 days and micronutrients needed 3-4 days. Combinatorial assessment showed that non-consecutive days including a weekend provided higher reliability—the optimal 3-day combination for carbohydrates (Monday-Wednesday-Saturday) achieved excellent reliability versus consecutive days. Weekend effects showed increases in energy and carbohydrates with concurrent decreases in water intake, effects most pronounced in younger participants and those with higher BMI.

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Conclusion: Our findings indicate that 3-4 days of dietary tracking, ideally non-consecutive and including both weekdays and weekend days, is generally sufficient for reliable estimation of energy and macronutrient intake. Our results refines FAO recommendations on nutrient-specific guidelines for more efficient study designs while maintaining reliability. The substantial differences between weekday and weekend consumption patterns emphasize the importance of including weekend days in dietary assessments to capture true dietary variability.

Disclosure of Interest: None declared