Background and objectives: To assess regional differences in the weight status and abdominal obesity among 13-year-old Greek adolescents. Design and setting: Cross-sectional, nationwide study in Greece. Patients and methods: A representative sample of 4833 13-year-old adolescents (50.7% boys) was recruited throughout the nine regional districts of Greece from 2010 to 2012. Basic anthropometry measurements (weight, height, and waist circumference) were obtained. Abdominal obesity and weight status were assessed according to the International Obesity Task Force criteria. Results: The majority of the sample had a healthy body weight (60.3%), 4.1% were underweight, 27.2% were overweight, and 8.5% were obese. For boys, the highest prevalence of underweight was recorded in Epirus, normal body weight on the Ionian Islands, overweight in Central Greece and Macedonia, and obesity on the Ionian Islands. Among girls, the highest underweight prevalence was on the Ionian Islands, normal body weight in Macedonia, overweight in Central Greece and Macedonia, and obesity in Crete. Abdominal obesity affected 12.9% of the sample, with the greatest prevalence among Cretan boys and Thracian girls. Additionally, residing on the Greek islands was associated with a higher prevalence of central adiposity. Conclusion: Greek 13-year-old adolescents who are subjected to geographical changes exhibit high obesity and abdominal obesity rates. This study provides evidence to design regionally tailored interventions that aim to tackle and prevent the disease among the nine regional districts in Greece.