Nutritional status is a key indicator of health and growth quality among school-age adolescents, and remains a public health concern in Indonesia given the double burden of malnutrition reported in national surveys. This study aimed to assess the nutritional status of eighth-grade students at SMP Perguruan Al-Ihsan Mulia Medan and to examine the association of sex and energy intake with nutritional status. This was an observational analytic study with a cross-sectional design, conducted in 2025 among 30 eighth-grade students selected through total sampling from an initial population of 60 students who had complete data on sex, nutritional status, and energy intake. Nutritional status was assessed using weight and height measurements converted into BMI-for-age (BAZ) z-scores, while energy intake was assessed through a single 24-hour dietary recall compared with the Recommended Dietary Allowance (RDA). Data were analyzed using the Chi-Square test. The results showed that most students were male (56.7%) and had good nutritional status (73.3%), while 20.0% were underweight and 6.7% were overweight. More than half of the students (53.3%) had inadequate energy intake. No significant association was found between sex and nutritional status (p = 0.206), whereas energy intake was significantly associated with nutritional status (p = 0.002). These findings suggest that energy intake, rather than sex, plays a more important role in determining the nutritional status of adolescents in this school. Nutrition education for students and parents, together with regular monitoring of nutritional status, is recommended to maintain and improve adolescent nutritional status.