BACKGROUND Obesity is a growing global health problem and a well-recognized risk factor for many medical conditions. This meta-analysis was conducted to assess the effect of obesity on overall complication occurrence, mortality, and hospital length of stay in patients with nonpathological lower limb trauma. METHODS The EMBASE, PUBMED, and MEDLINE electronic databases were searched from inception to April 1, 2020, for studies published in English. References cited by chosen studies were also checked manually for inclusion. Studies chosen for the analysis were prospective observational or retrospective cohort studies reporting on total complications of patients with acute traumatic, nonpathological, lower limb fractures that required internal fixation, with or without other underlying conditions. Two investigators independently reviewed the full text of eligible studies for inclusion and extracted data. Inconsistency was resolved through consultation with other authors. RESULTS Sixteen studies with 404,414 patients were investigated in this study. The data showed obesity was related with increased total complications (odds ratio [OR], 0.65; 95% confidence interval [CI], 0.51-0.83; p < 0.01), increased wound complications (OR, 0.41; 95% CI, 0.25-0.66; p < 0.01), and increased mortality rate (OR, 0.64; 95% CI, 0.45-0.91; p < 0.05). Six cohort studies also showed prolonged hospital length of stay in obese patients. CONCLUSION Our results suggest that obesity is associated with increased complication and mortality rates, as well as longer hospital length of stay in patients with lower-limb trauma who required surgical treatment. These findings may raise attention to optimize surgical technique and develop individualized treatment for obese patients.