Objective: Previous studies of sociodemographic and lifestyle correlates of dietary patterns among young adults have primarily focused on physical activity and smoking, with inconclusive results. This study aims to examine the associations between a broader range of lifestyles of young adults and their patterns of food consumption.Design: Cross-sectional.Setting: Brisbane, Australia.Participants: The data set are from a long running birth cohort study which commenced in 1981. Details of dietary intake and sociodemographic and lifestyle factors were from the 21-year follow-up of the Mater-University of Queensland Study of Pregnancy (MUSP) birth cohort. The effective cohort (n 2665, 57 % women) is of young adult offspring. Usual dietary intake was assessed using a Food Frequency Questionnaire (FFQ). Data on sociodemographic and lifestyle variables were obtained from self-reports.Results: Western and prudent dietary patterns were identified for the combined cohort of women and men using principal components analysis. Multivariable linear regression models were used to examine the associations between lifestyle variables and dietary patterns adjusting for potential confounders. Results from multivariable adjusted models showed that physical activity, watching TV and smoking were strongly associated with each dietary pattern; alcohol consumption and BMI showed weaker associations (P < 0·05 for all).Conclusions: Our study describes a clustering of unhealthy lifestyles in young adults. Young adults with unhealthy lifestyles less often adhere to a healthy prudent dietary pattern and more often an unhealthy Western pattern. Dietary preferences are enmeshed in a lifestyle matrix which includes physical activity, sedentary activity, smoking and alcohol consumption of young adults.

Adequate nutrition is essential from the early stages of life onward, to ensure proper growth and development as well as long-term health