Although dietary patterns are key to the management of childhood obesity, they are rarely assessed and thus poorly understood. This study examines preschoolers' dietary patterns and correlates 12 months after the start of obesity treatment (n = 99, mean age 5.2 years, 52% girls). A food frequency questionnaire (FFQ), the Child Eating Behavior Questionnaire (CEBQ), Child Feeding Questionnaire (CFQ) and Lifestyle Behavior Checklist (LBC) were answered by parents to assess children's food intake, eating behaviors, parental feeding practices, and obesity-related behaviors, respectively. Principal component analysis identified dietary patterns based on FFQ data. Through multiple linear regressions we examined correlations between a healthy (HD) and a less healthy (LHD) dietary pattern and mean scores of the CEBQ, CFQ, LBC scales as well as BMI z-scores. The reported intake of items in the LHD decreased after treatment while no differences were found for the HD. Children's eating behaviors, in particular food fussiness, showed consistent associations with diet (b =-0.39, 95% CI-0.63,-0.14 for HD and b = 0.41, 95% CI 0.15, 0.66 for LHD). Feeding practices and obesity-related behaviours were weakly associated with the dietary patterns (HD and Monitoring: b = 0.36, 95% CI 0.09, 0.62; LHD and Screen time b = 0.08, 95% CI 0.01, 0.15). Among the measured variables, eating behaviors had the largest impact on children's dietary patterns. The LHD was associated with a higher BMI z-score but no associations were found between changes in LHD intake and changes in BMI z-scores. Our findings suggest that decreasing food fussiness in children with obesity is key to positive dietary changes. Assessment of children's eating behaviors can help tailor dietary advice and provide support for families of children with obesity.