Background: The severity of acne vulgaris (AV), a relatively prevalent chronic inflammatory illness, can range from minor lesions to severe lesions that can cause deformities that significantly impact one's daily life. These days, obesity is also a very frequent health issue brought on by sedentary lifestyles and poor eating habits. Numerous systems are impacted, including the sebaceous glands' function and the skin barrier. This study aims to assess the relationship between body mass index (BMI) and occurrence and severity of acne vulgaris among adolescents

Methods: This Case control study was carried out in dermatology outpatient clinic at Zagazig University Hospitals, Egypt on adolescents with acne and apparently healthy control adolescents. Patients underwent complete history taking, physical and dermatological examination to determine severity of acne. Body mass index was calculated for both groups

Results: There is statistically significant difference between the studied groups regarding body mass index, as about (19%) of the patients with acne were obese compared to 4.9% of the patients in the control group. There is statistically significant positive correlation between body mass categories and grade of acne. Being overweight and obese significantly increases risk of severe/very severe acne by 6.67 folds

Conclusion: Obesity significantly associated with presence and severity of AV among adolescents. Lifestyle modification and weight reduction should be added in management of AV to improve outcome.