FIGURE 1.

Mediating effect of diet quality on the association between genetic susceptibility to obesity (PRS_BMI) and obesity measures (BMI and WC) in the Quebec Family Study.^{1 1}Values are β-coefficients ± SEs. n = 738 for BMI analysis and n = 737 for WC analysis. Analyses are performed on complete cases resulting in the exclusion of n = 12 participants with missing data on menopausal (n = 12), dieting (n = 1), or smoking status (n = 1) from analysis related to BMI and the exclusion of n = 11 participants with missing data on menopausal status from analysis related to WC. Mediation analyses are conducted using the Process Macro v. 3.3 for SAS that uses percentile bootstrap CIs to assess the mediating or indirect effect through which the PRS_BMI influences BMI (Figure 1A) or WC (Figure 1B). 95% CI for indirect effect are estimated through 5000 bootstrap samples. Mediation models are adjusted for age, sex (men, 0; women, 1), current dieting status (yes, 1; no, 0) menopausal status (yes, 1; no, 0), current smoking (yes, 1; no, 0) status, and misreporting of dietary intakes [(underreporting, yes, 1; no, 0) and (overreporting, yes, 1; no, 0)]. Diet quality assessed by the Nutrient Rich Food Index 6.3 (NRF6.3). a, association between the PRS_BMI and diet quality (mediator); b, association between diet quality (mediator) and BMI or WC adjusted for PRS_BMI; total effect (c), association between the PRS_BMI and BMI or WC without adjustment for diet quality (mediator); direct effect (c'), association between the PRS_BMI and BMI or WC adjusted for diet quality (mediator); indirect effect (ab), mediation effect; percentage of mediation: (indirect effect [ab]/total effect [c])×100. PRS, polygenic risk score; WC, waist circumference.