OBJECTIVE: The purpose of this study was to describe the weight-loss practices and weight-related issues reported by youth with diabetes, according to sex and diabetes type. RESEARCH DESIGN AND METHODS: A total of 1,742 female and 1,615 male youth aged 10-21 years with type 1 or type 2 diabetes completed a SEARCH for Diabetes in Youth study visit during which height, weight, and A1C were measured. A survey assessed weight-related issues and weight-loss practices. RESULTS: Although more common in youth with type 2 diabetes, youth with type 1 diabetes also reported weight-related concerns and had elevated BMI. Among youth who had ever tried to lose weight (n = 1,646), healthy weight-loss practices (diet [76.5%] and exercise [94.8%]) were the most common, whereas unhealthy practices (fasting [8.6%], using diet aids [7.5%], vomiting or laxative use [2.3%], and skipping insulin doses [4.2%]) were less common. In sex-specific multivariable models including age, race/ethnicity, diabetes type, BMI category, and glycemic control, obese females and overweight/obese males were more likely to report ever practicing any unhealthy weight-loss practice than normal-weight youth. These practices were associated with poor glycemic control for female but not male subjects. All unhealthy weight-loss practices except fasting were more common in female than in male subjects. Dieting, fasting, and using diet aids were all more common in youth with type 2 diabetes than in those with type 1 diabetes. CONCLUSIONS: Given the prevalence of overweight and obesity among youth with type 1 or type 2 diabetes, health care professionals caring for youth with diabetes need to pay particular attention to identifying youth, particularly females, with unhealthy weight-loss practices.