Background: The contribution of poor diet quality, as assessed by diet quality indices, to weight gain has not been fully elucidated. Objectives: To evaluate the association between diet quality and body weight change in adults by synthesizing the best available evidence on the relationship between overall diet quality and weight change over time. Inclusion criteria: Types of participants: Adults aged ≥ 18 years at baseline. Types of intervention(s)/phenomena of interest: Studies assessing dietary intake, total energy intake (TEI), energy density (ED) or total fat reported as the main exposure variable. Types of studies: Cohort studies with longitudinal data analysis. Types of outcomes: Studies reporting change in body weight as the outcome. Search strategy: A search of four databases (MEDLINE, CINAHL, EMBASE and Scopus) was performed from 1970 to March 2011 for English language cohort studies. Search terms included diet quality and weight status. Methodological quality: Study quality was assessed using standardised critical appraisal instruments from the Joanna Briggs Institute, Meta-Analysis of Statistics Assessment and Review Instrument (MAStARI). Data collection: The first author extracted the data from included studies using a standardised data extraction tool from JBI-MAStARI with a second reviewer checking the data extracted for accuracy. Data Synthesis: It was not possible to pool results in meta-analysis; thus this systematic review tabulated the results of the included studies. Results: From 2304 studies identified, 32 studies met all inclusion criteria. Eight focused on diet quality indexes, seven on dietary patterns identified from factor or cluster analysis, and 17 studies used nutrient-based approaches including fat intake, TEI or ED. Conclusions: Additional studies are needed that examine diet quality as a predictor of weight gain. Currently, the majority of studies use factor or cluster analysis to examine diet quality, but these comparisons represent very different dietary patterns. Currently no studies have applied factor or cluster analysis along with a diet quality index within the same population. This systematic review has highlighted the limitations and inconsistencies for the few studies that have examined EI, ED or total fat intake and weight change over time.
The JBI Database of Systematic Reviews and Implementation Reports Vol. 11, Issue 8, p. 272-316