A systematic review of the relationship between portion size and indexes of adiposity in children.

Research suggests that larger food portion sizes (PS) during a meal or snack increase daily energy intake in children. However, it remains unclear whether this 'PS effect' would lead to a sustained increase in consumption and affect body adiposity. This systematic review assesses the evidence for a relationship between served, consumed, and preferred PS (food or drink size in grams or kcal) and indexes of adiposity (e.g., BMI percentile, BMI z-scores) in children (< 19 years). A total of 17 articles were identified using six electronic databases (PsycINFO, MEDLINE, EMBASE, Web of Science, Cochrane Library, and ProQuest Dissertations & Theses Global). Articles were screened independently by 2 researchers; 21 studies were included (15 cross-sectional, 2 experimental, 1 case study, 1 longitudinal, and two interventions). A narrative review was conducted due to high levels of heterogeneity. Cross-sectional and experimental studies (n = 13) reported positive associations between PS and adiposity, but results differed according to the sex/gender of the participants and food type. Interventions (n = 2) showed that portion size reduction may be effective in reducing child adiposity. Due to the limited evidence on the causality and direction of the effect, and over-reliance on cross-sectional studies, more evidence on the longer-term impact of PS on indexes of body adiposity is required.