As a result of the increasing global incidence of obesity and related diseases, this study aims to investigate the prevalence of obesity and its correlation with eating disorder (ED) screening among medical students to develop effective prevention strategies and provide better outcomes for these students. We conducted a quantitative analytical cross-sectional study at the College of Medicine at King Saud University between November 2023 and February 2024. A stratified random sampling technique was utilized, enrolling a net number of 415 participants. Participants were asked several questions, including demographic information, weight, height, and past medical history, and were given a validated screening tool for EDs. Participants’ mean age was 21.4 ± 1.67 years, and 17.6% were considered obese. The prevalence of positive screening for EDs was 27.7%; it was more common in females (p = 0.013) and those who earned more than 1000 SAR per month (p = 0.011). Female students also exhibited almost twice the odds of having EDs than males (AOR = 1.957; 95% CI = 1.218–3.146; p = 0.006). Furthermore, non-obese students showed decreased odds of having EDs compared with obese students by at least 48% (AOR = 0.517; 95% CI = 0.287–0.929; p = 0.027). Our study revealed a concerning prevalence of ED symptoms and obesity among medical students, suggesting profound implications. Therefore, multicenter studies are needed to assess the generalizability of the results and apply the findings to targeted national campaigns and interventions tailored specifically to medical students.