Pediatric overweight and obesity continues to be a major public health concern. Once established it is difficult to treat; therefore well-designed and evaluated prevention interventions are vitally important. There is considerable evidence to suggest that obesity prevention initiatives can change children's behaviours and weight status over the short- or medium-term; however, there is far less evidence on which to judge the impact over the longer term. In response to the rise in short- and medium-term obesity prevention studies for children and adolescents over recent years, the Prevention Stream of the Australasian Child and Adolescent Obesity Research Network highlight five points as to why the dearth of obesity prevention studies with long-term follow-up should be urgently addressed. Furthermore, recommendations to strengthen the evidence base and outline key implications for research design in this area and the support required for long-term follow-up studies are detailed.