Adherence to a priori dietary patterns in relation to obesity: results from two cycles of the Canadian National Nutrition Survey

OBJECTIVE: To test whether adherence to the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) or a dietary pattern in-line with the 2015–2020 Dietary Guidelines for Americans (DGA) was associated with obesity. DESIGN: 24-h dietary recall data from the Canadian Community Health Survey (CCHS)-Nutrition, 2004 and 2015 cycles, were analysed. Diet quality index scores were computed for the Mediterranean-Style Dietary Pattern Score (MSDPS), a DASH index and the 2015 Dietary Guidelines for Americans Adherence Index (DGAI). Higher scores indicated greater adherence. Association between scores and obesity was examined using logistic regression, adjusting for age, sex, physical activity, smoking status, sequence of dietary recall and alcohol and energy intake. SETTING: Canada (excluding territories and the institutionalised population). PARTICIPANTS: Canadian adults (≥ 18 years), non-pregnant and non-breast-feeding; 11 748 from CCHS 2004 and 12 110 from CCHS 2015. The percentage of females in each sample was 50 %. RESULTS: Mean MSDPS, DASH and DGAI scores were marginally but significantly higher in CCHS 2015 than in CCHS 2004. Those affected by obesity obtained lower scores for all indexes in CCHS 2004 (OR 10th v. 90th percentile for DASH: 2·23 (95 % CI 1·50, 3·32), DGAI: 3·01 (95 % CI 1·98, 4·57), MSDPS: 2·02 (95 % CI 1·14, 3·58)). Similar results were observed in CCHS 2015; however, results for MSDPS were not significant (OR 10th v. 90th percentile for DASH: 2·45 (95 % CI 1·72, 3·49), DGAI: 2·73 (95 % CI 1·85, 4·03); MSDPS: 1·30 (95 % CI 0·82, 2·06)). CONCLUSION: Following DASH or the 2015–2020 DGA was associated with a lower likelihood of obesity. Findings do not indicate causation, as the data are cross-sectional.