The H4K Trial is a randomized controlled trial to improve children's body composition by testing a comprehensive, culturally and linguistically relevant, family-oriented intervention for overweight and obese Hispanic children (ages 6-11) in three pediatric clinics in San Antonio, Texas. The H4K trial will test the efficacy of a 6-month pediatric obesity management intervention (physician counseling plus telephone counseling, newsletters and text messages) compared to standard care (physician counseling only) on three outcomes: 1) body composition (i.e., waist circumference, weight and z-BMI); 2) insulin, glucose and cholesterol levels; and 3) behavior change in physical activity (PA), sedentary behavior and consumption of sugary beverages and fruits and vegetables. The investigators will recruit 230 overweight and obese children—and a parent or guardian for each—and randomize them to the H4K intervention (n = 115 child/parent dyads) or standard care (n = 115 child/parent dyads). The investigators hypothesize that intervention children will significantly improve their body composition, increased their PA levels and diet quality (more fruits and vegetables and less sugary beverages), and decrease their sedentary activity, compared to children in standard care. If successful, this study will generate new scientific knowledge about effective Hispanic family-based approaches for obesity prevention with high potential for replication in underserved areas across the nation.