Guoqiang Liu,1,* Kun Yang,1,* Chen Wang,1,2 Jin Yang1 

1Department of Endocrinology and Metabolism, State Key Laboratory of Female Fertility Promotion, Peking University Third Hospital, Beijing, 100191, People’s Republic of China; 2Department of Clinical Nutrition, Peking University Third Hospital, Beijing, 100191, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Chen Wang; Jin Yang, Email starsands2003@126.com; yangjin@bjmu.edu.cn

Background: Normal weight obesity (NWO) is defined as normal body mass index (BMI) but increased body fat percentage (BF%). NWO population tend to develop metabolic syndrome, type 2 diabetes and cardiovascular disease. BF% is the key parameter applied in the evaluation of NWO. The exact prevalence of NWO and the cutoff point for the diagnosis of NWO are not well established. Diet and physical activity interventions are the main approach for NWO management. Smartphone apps are widely used for their effectiveness and individualization, making them ideal tool for simplifying the follow-up process in behavioral interventions for both investigators and participants.
Methods: A single center, prospective, randomized trial will be conducted in Beijing, China. The aim of this 12-week trial is to assess the efficacy of different lifestyle interventions, including diet control only, aerobic training only, resistance training only, and a combination of aerobic and resistance training based on a smartphone app on BF% and metabolic parameters in the NWO population. The primary outcome is the change of BF% between the baseline and 12 weeks post-intervention. The secondary outcomes include changes in measures of anthropometry, blood glucose, insulin, lipids and uric acid between the baseline and 12 weeks of intervention. A sample size of 200 subjects with normal BMI and glucose abnormality confirmed by oral glucose tolerance test will be recruited. Two follow-ups face-to-face and five follow-ups via smartphone app will be included in this trial. Statistical analyses will focus on the differences among different lifestyle interventions and the cutoff point of BF% for diagnosis of NWO.
Discussion: This trial will provide evidence of the efficacy of lifestyle interventions based on smartphone app. The differences in effect among different lifestyle intervention groups will be elucidated. It will be helpful to propose the cutoff point of BF% for diagnosis of NWO.
Trial Registration Number: This study was registered with chictr.org.cn: ChiCTR2200063583.

Keywords: normal weight obesity, body fat percentage, randomized controlled trial, smartphone app