Background: Dietary pattern analysis represents a departure from the traditional focus on single foods and nutrients and provides a comprehensive understanding of the role of the diet in chronic disease prevention and etiology. Dietary patterns of Canadians have not been evaluated comprehensively with the use of an updated a priori dietary quality index.

Objectives: We aimed to update the Dietary Guidelines for Americans Adherence Index (DGAI) on the basis of the 2015 Dietary Guidelines for Americans (DGA), to evaluate the construct validity and reliability of the revised index, and to examine whether closer adherence to this index is associated with a lower risk of obesity with or without an accompanying chronic disease.

Design: Data from 11,748 participants (≥18 y of age) in the cross-sectional Canadian Community Health Survey cycle 2.2 were used in weighted multivariate analyses. Multinomial logistic regression was used to test the association between diet quality and obesity risk.

Results: With the use of principal component analyses, the multidimensionality of the 2015 DGAI was confirmed, and its reliability was shown with a high Cronbach's α = 0.75. Moving from the first to the fourth (healthiest) quartile of the 2015 DGAI score, there was a trend toward decreased energy (2492 ± 26 compared with 2403 ± 22 kcal, respectively; ±SE) and nutrients of concern (e.g., sodium), whereas intakes of beneficial nutrients increased (P-trend < 0.05). In the age- and sex-adjusted model, a lack of adherence to the 2015 DGA recommendations increased the OR of being unhealthy obese from 1.42 (95% CI: 1.02, 1.99) in quartile 3 to 2.08 (95% CI: 1.49, 2.90) in quartile 2 to 2.31 (95% CI: 1.65, 3.23) in the first quartile of the 2015 DGAI score, compared with the fourth quartile (healthiest) (P-trend < 0.0001). The odds of being obese without a chronic disease (healthy obese) and having a chronic disease without being obese also increased in the lowest DGAI quartile compared with the highest DGAI quartile, albeit not as much as in the unhealthy obese group.

Conclusion: The 2015 DGAI provides a valid and reliable measure of diet quality among Canadians.