Research
Adherence
Dietary self-report instruments (FFQs and 24-hour recalls) significantly underestimate absolute energy and protein intake, with under-reporting rates of approximately 28% for FFQs and 15% for single 24-hour recalls, while over-reporting protein density.
Do not trust the absolute calorie or protein numbers from food diaries or apps. They consistently underestimate intake by 15-30%. If you need to know your true intake, use biomarkers (like doubly labeled water) or apply statistical calibration equations that account for your BMI, age, and sex.
StrongRefutesHIGH confidence
The average rate of under-reporting of energy intake was 28% with a FFQ and 15% with a single 24-hour recall, but the percentages were lower for protein.
Why this rating
Pooled analysis of 5 large validation studies using recovery biomarkers (gold standard).
Source
Pooled Results From 5 Validation Studies of Dietary Self-Report Instruments Using Recovery Biomarkers for Energy and Protein Intake
Laurence S. Freedman et al. · American Journal of Epidemiology · 2014
Meta-analysis · 5 studiesCited 524×
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