This is a pilot testing the feasibility of the 'REpurposing BOtulinum Toxin in Treatment of Obesity in Adolescents' trial (ReBOO-trial). The full-scale ReBOO will further investigate safety and efficacy of intragastric injections of botulinum toxin A into the antrum area of the stomach. These injections will be repeated every six months.

The study sample will be adolescents with obesity who have not responded to standard conservative treatment.

Inclusion Criteria:

1. Written (signed) informed consent
2. Age and gender adjusted body mass index (ISO-BMI) ≥ 35 or ISO-BMI > 30 with comorbidities including hypertension, non-alcoholic fatty liver disease, hyperlipidemia or impaired glucose tolerance
3. Having partaken in a comprehensive multi-disciplinary lifestyle treatment for obesity of duration 12 months or more, without achieving a clinically significant weight loss (non-responder)

Exclusion Criteria:

1. Known hypersensitivity to excipients in the investigational medicine product (IMP)
2. Neuromuscular disorders
3. History of dysphagia
4. History of aspiration tendency or aspiration pneumonia
5. Known lung disease under continuous treatment
6. Congenital or acquired heart disease
7. Previous experience of side effects to Botulinum toxin type A
8. Present gastric diseases or dysfunction
9. Previous bariatric surgery
10. History of cancer
11. Serious binge eating disorder
12. Untreated hypothyroidism
13. Use of aminoglycoside antibiotics or spectinomycin in the week prior to injection, or any other medicinal product that interfere with neuromuscular transmission (neuromuscular blocking agents)
14. Medication known to affect appetite
15. Syndromic obesity
16. Mentally immature to a degree that there is doubt about the subject's ability to assent
17. Issues relating to language or culture that may complicate trial participation
18. Pregnancy or breastfeeding