Study protocol for a randomized clinical trial to reduce weight among youth with obesity using time-restricted eating: the TRECO study

Childhood obesity is a major metabolic disorder affecting approximately 20% of children and adolescents. Because around 80% of obese adolescents will still be obese in adulthood, action to reduce obesity in children and adolescents is needed. Although a caloric-restricted diet (CRD) is the primary treatment for obesity, adherence to CRD typically declines over time, and many individuals who lose weight with this strategy regain it. Accumulating evidence suggests that time-restricted eating (TRE) has a significant impact on weight loss in adults with obesity. However, the weight-loss effect of TRE on childhood obesity remains largely lacking in trial evidence, due to the significant differences in metabolic states and eating behavior plasticity between children and adults. We will conduct an open-label, blinded-endpoint, parallel design, randomized controlled trial to assess the efficacy of 12-hour TRE on weight loss in children with obesity compared to CRD. A total of 128 patients with childhood obesity (8–17 years old, BMI-Z value > 2) will be enrolled and allocated into two arms by block randomization stratified by sex and age. Standardized lifestyle counseling will be provided for all participants to enhance physical activity and healthy eating habits. Based on the standardized lifestyle counseling, 12-hour TRE and CRD will be administered to the experimental and control groups, respectively. The short-term effect will be evaluated after 12 weeks of intervention by comparing the magnitude of BMI-Z reduction from baseline between the two groups. The intervention will be extended to 48 weeks to test the long-term effect and adherence. In the TRE program, participants only need to consider the timing of meals and the duration of fasting. Available evidence suggests that the earlier dinner ends, the better, but the duration of fasting is not as long as it should be, and the longer it is, the worse compliance may be. Although several trials have been conducted to examine the weight loss effects of 14- and 16-hour TRE in childhood obesity, no study has been designed regarding 12-hour TRE, while 12-hour fasting is relatively more acceptable in children. ClinicalTrials.gov ID: NCT06583447. Registered 29 August 2024. https://clinicaltrials.gov/study/NCT06583447. • The weight-loss effect of TRE has been demonstrated in adults rather than children with obesity. This study will provide comprehensive evidence for the efficacy of TRE in childhood obesity for the first time. • The key points of TRE include the timing of meals and the duration of fasting. Both of them remain ambiguous in adults and unclear in children. Based on the existing research, this study proposes an acceptable TRE program for children that involves fasting for at least 12 h, with the last meal no later than 7:00 p.m. • Existing studies mainly focused on the short-term effect of TRE on weight loss. This study will examine the long-term impact of TRE on weight loss and other metabolic factors in children with obesity after a 1-year intervention.