INTRODUCTION: Although weight loss is known to alleviate urinary incontinence (UI) symptoms, the effects of sex and body size on this relationship remain insufficiently explored. MATERIALS AND METHODS: We analyzed data from the National Health and Nutrition Examination Survey (NHANES) 2007-2018, comprising 28,161 participants. Weighted logistic regression analysis, fitted curves, and subgroup analysis were used to assess the association between the percentage of weight loss and UI. Propensity score matching (PSM) was performed to account for potential confounding factors. RESULTS: After PSM, multivariate logistic regression showed an inverse relationship between weight loss percentage and UI risk (odds ratio [OR] = 0.97, 95% confidence interval [CI]: 0.94-0.99). Compared with weight loss percentages < 0%, the risk of UI significantly decreased with weight loss percentages > 5% (weight loss percentage 5.1-10%: OR = 0.83, 95% CI: 0.70-1.00; weight loss percentage 10.1-15%: OR = 0.73, 95% CI: 0.55-0.97; weight loss percentage > 15%: OR = 0.52, 95% CI: 0.39-0.70). Furthermore, subgroup analysis indicated that this relationship was more significant in males and non-overweight/non-obese populations. CONCLUSION: There was an inverse relationship between weight loss percentage and UI risk, with noticeable differences based on sex and body size. However, these findings warrant further investigation.