Background: urgent development of effective interventions to prevent rapidly rising childhood obesity in China is needed. Methods: Between May 2010 and December 2013, a cluster randomized controlled trial was conducted among 4 graders in eight urban primary schools randomly assigned to intervention or control groups in Nanjing, China. A multi-component intervention program was implemented within the treatment group, while students in the control group followed their usual health education curriculum without additional intervention. Results: At baseline, 638 and 544 students were enrolled in the intervention and control group, respectively. The prevalence of excess body weight was 26.8%, with 27.4% in the intervention group and 26.1% in the control group (p=0.61). The mean (SD) BMI and WC was 18.7 (3.0) and 63.0 (9.2) for participants in intervention schools, and 18.5 (2.9) and 63.6 (8.7) for students in control group, separately (p=0.24 and 0.41, respectively). Compared to those who were not aware of what lifestyle/behavior factors were unhealthy, students who were aware of the unhealthy lifestyle/ behavior factors consumed fewer fried snacks (0.46±0.76 serves/week vs 0.65±0.91 serves/week;
