Globally, increasing prevalence of obesity has been observed, not just amongst adults but also in children. Studies have suggested that early development of obesity in childhood is associated with obesity in adulthood and development of chronic illnesses. It is thus important that factors associated with the rising prevalence of obesity amongst children are investigated, so that early interventions can be put in place to address the issue. While the causes contributing to obesity are complex, healthy eating is one of the most important and modifiable risk factors to address this issue. Traditionally, studies have been conducted to understand specific food group or nutrient and the association with obesity. However, in recent decades, food systems have undergone major changes that have led to a rising availability of ultra-processed foods globally. Under the NOVA food processing classification, ultra-processed foods are defined as industrial products made with many ingredients not accessible in domestic kitchen and typically contain a myriad of artificial additives. While there are growing evidence that the consumption of ultra-processed foods are linked to obesity in adults, this has not been examined in children except for few cohort studies with short follow up time. Therefore, this project aims to investigate the link between childhood consumption of ultra-processed foods and the development of overweight and obesity from childhood to early adulthood in the ALSPAC birth cohort. The results of this study will address an important gap in literature and also provide valuable insights to help shape future policies in tackling childhood obesity.