Background : In 2016 more than 1.9 billion adults aged 18 years and over were overweight. More than 650 million adults are obese. Overall, around 13% of the world's adult population is obese in 2016. The prevalence of obesity worldwide has nearly tripled between 1975 and 2016. In 2016, an estimated 41 million children under 5 years were overweight or obese and more than 340 million children and adolescents aged 5-19 were overweight or obese. The prevalence of obesity is higher in people with intellectual disabilities than the general population. Purpose : Purpose this study was to determine factors that cause obesity in people with intellectual disabilities. Methods : Relevant health databases including EBSCO, PUBMED, Proquest and Scholar are sought using a combination of themes: intellectual disability, obesity, adults, and young people. Results : Based on the results of the article review the factors that influence obesity in people with intellectual disabilities are poverty, physical activity, alcohol, dietary habits, living environment, drug use, gender, age, parental education, down syndrome Conclusion :Tthe factors that cause obesity in people with intellectual disabilities are diet, physical activity, poverty, alcohol, living enviroment, drug use, gender, age, parental education and down syndrome.