Abstract Background Studies have suggested that obesity is linked within families and that successful interventions involve both the parent and child with obesity. However little information exists regarding similarities in adiposity and weight loss between the parent and child, especially in low socio-economic ethnically diverse households. Methods The purpose of this study was to examine the relationships between the changes from baseline over time in adiposity, weight, health behaviors, and self-efficacy in children (n = 184) and parents (n = 184) participating in an 18-month weight loss program. Within the intervention group only and for each post-baseline time point, Pearson correlation coefficients were computed for children’s changes (from baseline) in adiposity, weight, health behaviors, and self-efficacy, with their parents’ corresponding changes from baseline, to determine how strongly the dyads were correlated. Results At the completion of 18 months, the intervention group parents demonstrated strong positive correlations between parent and child change in waist circumference (r = 0.409, p < 0.001), triceps (r = 0.332, p < 0.001), and subscapular (r = 0.292, p = 0.002) skinfolds. There were no significant correlations between weight, health behaviors, eating, and exercise self-efficacy. Conclusions The results suggest that in the Southern United States low-income parents and their children with obesity are strongly correlated. Trial registration NCT01378806 Retrospectively Registered on June 22, 2011.