Inclusion | Aged 14–18 years. |
Body mass index ≥30 kg/m2. |
Postpubertal (Tanner stage 5). |
Exclusion | Gastrointestinal disease (including inflammatory bowel disease or coeliac disease). |
Use of regular medications that may influence weight, metabolism or the gut microbiome (including oral oestrogen-containing contraceptives, antidepressants, glucose-lowering drugs, diet drugs, as well as inhaled, topical or oral steroids). |
Consumption of probiotics. |
Type 1 diabetes, type 2 diabetes or monogenic diabetes |
Chronic diseases that could affect the primary outcome (other than obesity-related conditions). |
Food allergies. |
Allergy to macrogol (active ingredient in the bowel preparation product). |
Allergy to any over-the-counter medication. |
No antibiotic usage for 3 months prior to trial treatment. |