The aim of this study was to evaluate the differences between adolescents with a high or low risk of developing an eating disorder (ED) in different health behaviors (eating habits, physical activity and the consumption of substances) per gender. The EAT-40 and the Inventory of Behavioral Health in Scholars were applied to 2142 middle school students from Alicante (Spain), of whom 52.8% were girls and 47.2% were boys, with an average age of 13.92 years old (Sd = 1.34). Results indicated that girls with a high risk of developing an ED consumed fewer meals, ate fewer unhealthy foods, followed more diets and paid more attention to nutritional components. Furthermore, they also performed more physical activity with the objective of losing weight, and consumed more tobacco, alcohol and medicines. Boys at high risk of developing an ED followed more diets and paid more attention to nutritional components. For boys, no more differences were found. These results suggest that any program directed at the prevention of ED should not only include nutritional education, but should also seek to promote regular physical activity with objectives other than weight loss or the burning of calories.