A school-based, multi-faceted health promotion programme to prevent obesity among children: protocol of a cluster-randomised controlled trial (the DECIDE-Children study) by Qin Li, Hong Zhou, Fang Zhang, Zheng Liu, Pei Gao, Yangfeng Wu, Yi Song, Shuang Zhou, Wen-Yi Niu, Xiangxian Feng, Yi Lin, Aiyu Gao, Hai Fang, Hui-Juan Li, Haijun Wang, Hai-Jun Wang, Li-Zi Lin, Qiang Feng, Chen-Xiong Li, Wen-Hao Li, Chu-Yao Jin, Yu Cheng, Lan Cheng Di Wang, Xiang-Rong Xu, Jie-Yun Song, Ai-Yu Gao, Hai-Hua Chen, Li-Jia Shang, Run-Ze Chen, Xiang-Xian Feng, Jian-hui Yuan, Li-fen Duan, Chun-Xia Xu, Guo-Qin Yang, Zheng Zhang