Validated Food Quantification Aids for Dietary Assessment: A Systematic Review

CONTEXT: Accurate dietary intake measurement relies on the precise quantification of food consumption. However, numerous portion size aids are limited by insufficient validity, reliability, or feasibility measures. OBJECTIVE: The objective of this systematic review was to systematically identify and evaluate the characteristics and methodological quality of validation studies for food quantification aids. DATA SOURCES: Four electronic databases (PubMed, Web of Science, Scopus, and EMBASE) were searched from inception until March 2025. Peer-reviewed original articles of studies on the validation of food quantification aids were included and assessed for quality. DATA EXTRACTION: Two authors independently performed data extraction. A third reviewer resolved any discrepancies/uncertainties between the 2 reviewers through consensus. The data extracted included study details (ie, author, country, food quantification aids, food tested, number of participants, research setting, weight, and percentage differences) and the quality of the validation. DATA ANALYSIS: After screening 22 647 records, 74 articles were included, encompassing 136 food quantification aids. The study details and quality were summarized and compared in tables and figures. RESULTS: The aids were categorized into 8 groups, with the majority (57%) classified as standardized food photographs. Others were photographs taken by participants (6%), household measures (8%), food models (4%), measuring devices (11%), standard food portions (4%), 2D/3D aids (8%), and virtual reality tools (2%). Most of the aids (65%) were physical (printed), and 33% were digital. The mean percentage error ranged from a 92% underestimation to a 413% overestimation across all aids, and the most accurate result was observed among standardized photographs. Variation was observed in the validation methods and study characteristics. The quality assessment tool categorized 20% of the studies as highly appropriate. Nine studies assessed usability, reporting higher-than-average positive ratings. CONCLUSIONS: Overall, a large variation was noted in the validation methodology and the accuracy of most of the aids. Standardized guidelines for validating food quantification aids should be established. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42023402714.