Double-blinded, 6 Months Study With Bydureon® or Placebo in Adolescents With Obesity to Explore Changes in BMI

Inclusion Criteria: 1. Signed informed consent prior to any study-specific procedures. 2. Males or females of age 10-18 years and 5 months. 3. Obesity (BMI SDS \> 2.0 or age-adapted BMI \> 30 kg/m2), according to WHO. 4. Not sexually active or usage of adequate anticonception. Female subjects must also have negative pregnancy tests. Methods that can achieve a failure rate of less than 1% per year (Pearl index \<1), when used consistently and correctly, are considered as highly effective birth control methods. Such methods include: * Combined (oestrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation: * oral * intravaginal * transdermal * Progestogen-only hormonal contraception associated with inhibition of ovulation: * oral * injectable * implantable * Intrauterine device (IUD) * Intrauterine hormone-releasing system (IUS) * Bilateral tubal occlusion * Vasectomised partner Sexual abstinence (if refraining from heterosexual intercourse during the entire period of risk associated with the study treatments. The reliability of sexual abstinence needs to be evaluated in relation to the preferred and usual lifestyle of the subject). 5. Ability to understand and comply with the requirements of the study. Exclusion Criteria: 1. Known syndromal obesity, such as Prader-Willi syndrome, Laurence-Moon syndrome or Bardet-Biedl syndrome. 2. Pregnancy or lactation. 3. Indigestion-causing diseases. 4. Severe gastrointestinal disease. 5. Total or partial gastric or small intestine resection. 6. Type 1 or Type 2 diabetes mellitus. 7. Kidney disease (acute or chronic, according to physician (Creatinin/Urea/Cystatin-C for Schwartz Calculation)). 8. Hypo-/Hyperthyroidism, unless under stable treatment. 9. Severe Vitamin D insufficiency, unless under stable treatment. 10. Abnormal QT interval. 11. Clinically significant abnormal laboratory values, e.g. Triglycerides \> 400 mg/dl (Salzburg) or \> 4,5 mmol/L (Uppsala), Amylase \> 300 U/L (Salzburg) or \> 5,1 µkat/L (Uppsala), Lipase \> 180 U/L (Salzburg) or \> 15 µkat/L (Uppsala) or Calcitonin \> 11.7 pg/ml (Salzburg) or \> 3,4 pmol/L (Uppsala) for females and \> 17 pg/ml (Salzburg) or \> 5,0 pmol/L (Uppsala) for males. 12. Severe depression, severe anxiety or other psychiatric disorder referred to or undergoing special treatment, as judged by the investigator. 13. Severe sleep apnea (defined clinically). 14. Chronic diseases, as judged by the investigator. 15. Metformin treatment within 3 months prior to screening or concomitant medication influencing blood glucose (e.g. metformin and acarbose), influencing other parameters of metabolic syndrome (e.g. orlistat) or interfering with the investigational medicinal product. 16. Steroid treatment (oral or injected). 17. Concomitant medication addressing attention disorders. 18. Antidepressants that can lead to weight gain, as judged by the investigator. 19. Hypersensitivity to exenatide or to any of the excipients. 20. Pacemaker or metal implant that may interfere with Magnetic Resonance Imaging (MRI). 21. Claustrophobia (Uppsala and Salzburg) or abdominal diameter exceeding an MR gantry diameter of 70 cm (Salzburg). 22. Current or prior (within 3 months) participation in another clinical study involving an Investigational Medicinal Product (IMP). 23. A personal or family history of Medullary Thyroid Carcinoma (MTC) 24. A personal or family history of Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).