Objective: To assess the relationship between diet quality and body mass index (BMI) in Canadian adults.
Methods: We used confidential, individual-level data on 6325 adult men and 7211 nonpregnant adult women from the 2004 Canadian Community Health Survey to construct 2 diet quality indices (the Diet Quality Index [DQI] and and the Healthy Eating Index [HEI]) and BMI. After adjusting for known observable confounders, a latent class modeling analysis was conducted to account for unobservable confounders.
Results: We found that there were 2 latent classes (low-BMI and high-BMI components), and that DQI and HEI indices were negatively associated with BMI in the high-BMI component. In the high-BMI component, a one-unit increase in DQI score is associated with a 0.053 kg/m(2) decrease in BMI, whereas a one-unit increase in HEI score is associated with a 0.095 kg/m(2) decrease in BMI. Subgroup analyses revealed that the association between diet quality and obesity was stronger in women.
Conclusions: Diet quality is associated with lower BMI in high-BMI individuals in Canada. Diet quality exhibits a distinct association in each latent class; this association is stronger in women. Latent class analysis offers a superior methodological framework in understanding the modifiable risk factors for obesity.