Intensive Weight Loss Intervention Versus Usual Care for Adults With Severe and Complex Obesity

Please note that participants need to be invited in order to take part in the trial Inclusion Criteria: 1. Age ≥18 years and ≤60 years old at screening. 2. Has severe and complex obesity i.e. BMI\>35 or \>32.5 in people with South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family backgrounds and with one or more of these specific adiposity-related chronic diseases of cardiovascular disease, type 2 diabetes, hypertension, non-alcoholic steatosis, or sleep apnoea. 3. Provides informed consent. Exclusion Criteria: 1. Intending to become pregnant in the next two years or pregnant or breastfeeding. 2. Use of WLM or GLP-1 agonist treatment within the last three months. 3. Currently being treated for cancer other than oestrogen antagonist therapy or non-melanoma skin cancer. 4. Prior bariatric surgery, not including laparoscopic gastric banding, intragastric balloons or duodenal-jejunal bypass sleeve (Endobarrier™ or similar) if the device has been removed \>1 year before screening. 5. Diagnosis of or treatment for severe eating disorder within the last 6 months. 6. Any other disease that markedly compromises the participant's ability to adhere to the treatment programme or follow-up or is likely to mean that weight loss will not improve the person's length or quality of life, such as conditions limiting life expectancy. 7. Conditions that contraindicate or complicate TDR (including type 1 diabetes or other diabetes requiring insulin therapy, phenylketonuria, or other conditions requiring special diets). 8. Conditions that contraindicate or complicate GLP-1 treatment (including history of pancreatitis) 9. Taking part in other research involving multidisciplinary obesity treatment would compromise participation in this trial. 10. Another member of the household enrolled in the trial.