The aims of the current study were to explore possible gender differences in weight misperception, self-reported physical fitness, and dieting, and to analyze the relationship between these variables and others, such as self-esteem, body appreciation, general mental health, and eating- and body image-related variables among adolescents. In addition, the specific risk for eating disorders was examined, as well as the possible clusters with respect to the risk status. The sample comprised 655 students, 313 females and 342 males, aged 16.22 ± 4.58. Different scales of perceived overweight, self-reported physical fitness and dieting together with the Body Mass Index (BMI) were considered along with instruments such as the International Physical Activity Questionnaire (IPAQ), General Health Questionnaire (GHQ-28), Self-Esteem Scale (SES), Body Appreciation Scale (BAS) and Eating Disorders Inventory-2 (EDI-2). Since some gender differences were found with respect to these adolescent groups, it is necessary to design prevention programs that not only focus on traditional factors such as BMI or body image, but also on elements like weight perception, self-reported fitness and nutritional education.