Record levels of obesity in children and adolescents are predictable in light of powerful conditions that promote high consumption of calorie-dense, nutrient-poor foods and discourage physical activity. Default conditions for youth are dangerous, and include multiple and relentless forms of marketing, poor foods promoted in schools, and a variety of other conditions that undermine personal resources, individual responsibility, and parental authority. This article discusses how optimal defaults can be created using five issues as examples: framing of the obesity issue, treating versus preventing obesity, nutrition in schools, marketing, and addressing weight bias and discrimination. By adopting a public health approach that addresses the conditions causing obesity, there is hope of reversing troubling trends in prevalence.