BackgroundChildhood adiposity has increased dramatically in the last few decades and is an important predictor of adulthood chronic disease. Later eating rhythm, termed night eating (NE), is increasingly prevalent in adults; however, the prevalence of NE in children and relationship between NE and adiposity in children still remains uncertain. The aim of this work is to review the association between adiposity in children and adolescents and NE, in terms of calorie intake, timing and meal frequency in the evening/night.MethodsThe Cochrane library, CINAHL, Embase, MEDLINE (via OVID) and Web of Science databases will be searched from inception to November 2019 for randomised controlled trials (RCTs) and observational studies (cohort, cross-sectional and case-control studies) which investigate the association between later vs. earlier timing of food intake at night or relatively more vs. less energy intake in any eating occasions or time period after 4 pm on adiposity in children and adolescents (4–18 years). The outcomes will be body mass index (BMI)/BMI standard deviation score (BMI-SDS or BMI Z-score), waist circumference (WC), fat mass index (FMI)/percentage of body fat (%BF) or waist to hip ratio (WHR). No language restriction will be applied. Screening for eligibility from the title and abstracts and data extraction from the full texts will be carried out by two reviewers independently. References listed in the included studies will be hand-searched for any additional articles. The quality of included RCT studies will be assessed using Revised Cochrane Risk of Bias tool (RoB 2), and of observational studies using Newcastle Ottawa scale. A qualitative synthesis of the results will be presented, and meta-analysis will be conducted, where appropriate.DiscussionThe planned systematic review will investigate the association between later eating rhythm and adiposity in children and adolescents. Understanding the best meal size, timing of energy intake and meal frequency across the evening time for maintaining healthy weight in children is important in order to give parents the best advice to help prevent adulthood obesity and associated chronic diseases in their children.Systematic review registrationPROSPERO CRD42019134187.