Interview with David S. Ludwig, MD, PhD, author of Weight Loss Strategies for Adolescents: A 14-Year-Old Struggling to Lose Weight. Summary Points: 1. Childhood obesity arises from a complex interplay of biology, behavior, and the environment. Consequently, successful treatment requires targeting multiple determinants of body weight. 2. Family-based treatment offers the most immediate and effective approach for childhood obesity, with benefits for all family members. 3. Ultimately, the solution to the obesity epidemic will require a comprehensive public health strategy to make the social environment healthier for children and adults.