Background: The prevalence of being overweight and obese is increasing not just in the general population but also in individuals with intellectual disability (ID). Therefore, a need to identify factors contributing to overweight/obesity arises as this population is escalating. Materials and Methods: This narrative review article summarizes pertinent research focusing on prevalence and the potential factors associated with overweight and obesity in adults with intellectual disability during the past decade. Results: Prevalence of being overweight and obese among adults with intellectual disability is reportedly 28%-71% and 17%-43%, respectively. Factors increasing the susceptibility of being overweight or obese have been identified as female gender, increasing age, having a certain diagnosis, mild intellectual disability, as well as living independently/with family, consuming certain prescription medications, and non-participation in physical activities. Conclusion: Identification of the potential risk factors associated with being overweight and obese in this population will help tackle the challenges faced by this growing adult population with intellectual disability.