Statisticians and investigators drawing conclusions will be fully blinded. The statistical analyses will be conducted with the intervention groups coded as e.g., 'A' and 'B'. The Steering Committee will write two abstracts while the blinding is intact; one assuming the experimental intervention group is 'A' and the control intervention group is 'B', and one assuming the opposite. After these two abstracts have both obtained consensus, the code will be broken by the data manager. primaryPurpose: TREATMENT masking: DOUBLE whoMasked: INVESTIGATOR whoMasked: OUTCOMES_ASSESSOR count: 600 type: ESTIMATED name: Intensive weight loss intervention name: Usual care measure: MetS-Z measure: Weight measure: Short-Form-36, mental component score measure: Gait speed measure: Weight loss (20%) measure: SAE measure: Incident eating disorders measure: Bone mineral density (BMD) assessed by DXA measure: Body composition - waist circumference measure: Body composition - fat percentage measure: Body composition - weight loss (10%) measure: Physical functioning - SENS measure: Physical functioning - SF-36 measure: Physical functioning - sit to stand test measure: Sleep measure: Medications during the intervention period measure: Metabolic health - blood pressure measure: Metabolic health - pulse measure: Metabolic health - Hb1Ac measure: Metabolic health - insulin measure: Metabolic health - HOMA2-IR measure: Metabolic health - lipids measure: Metabolic health - eGFR measure: Metabolic health - hsCRP measure: Metabolic health - Fib4 measure: Metabolic health - proteinuria measure: Metabolic health - TSH measure: Mental health - MDI measure: Mental health - WBIS-M measure: Mental health - EDE-Q measure: Labour market attachment - WPAI measure: Labour market attachment - days of sick leave measure: Genetic profiles' (using comprehensive genetic mapping) association with the metabolic and/or weight loss response to IWL vs usual care measure: Health economy: Within-trial cost-effectiveness analysis - quality of life, index score measure: Health economy: Within-trial cost-effectiveness analysis - quality of life, VAS measure: Health economy: Within-trial cost-effectiveness analysis - costs measure: Health economy: Within-trial cost-effectiveness analysis - QALY measure: Health economy: Model-based cost-effectiveness analysis - QALY measure: Health economy: Model-based cost-effectiveness analysis - healthcare costs measure: Health economy: Model-based cost-effectiveness analysis - cost effectiveness ratios measure: Long-term effects - mortality and major cardiovascular disease (CVD) measure: Long-term effects - prescription patterns measure: Long-term effects - incident cancer measure: Long-term effects - fracture risk measure: Long-term effects - health economic and labour market attachment, employment status measure: Long-term effects - health economic and labour market attachment, salary measure: Long-term effects - health economic and labour market attachment, absence measure: Long-term effects - health economic and labour market attachment, sick leave measure: Long-term effects - health economic and labour market attachment, long-term sick leave sex: ALL minimumAge: 18 Years maximumAge: 60 Years stdAges: ADULT facility: Frederiksberg kommune: Social-, Sundheds- og Arbejdsmarkedsområdet status: NOT_YET_RECRUITING city: Frederiksberg zip: 2000 country: Denmark name: Addie J Frederiksen role: CONTACT lat: 55.67938 lon: 12.53463 facility: The Parker Institute, Copenhagen University Hospital - Bispebjerg and Frederiksberg status: NOT_YET_RECRUITING city: Frederiksberg zip: 2000 country: Denmark name: Sofus C Larsen role: CONTACT lat: 55.67938 lon: 12.53463 facility: Hvidovre kommune: Center for Sundhed og Ældre, Hvidovre Sundhedscenter, Sundhed og Forebyggelse status: NOT_YET_RECRUITING city: Hvidovre zip: 2650 country: Denmark name: Maria Bleiback Clausen role: CONTACT lat: 55.65719 lon: 12.47364 facility: The Department of Medicine and the Gastro Unit, Copenhagen University Hospital - Amager and Hvidovre status: RECRUITING city: Hvidovre zip: 2650 country: Denmark name: Carsten Dirksen role: CONTACT lat: 55.65719 lon: 12.47364 facility: Gladsaxe kommune: Social- og Sundhedsforvaltningen, Sundhed og Rehabilitering status: NOT_YET_RECRUITING city: Søborg zip: 2860 country: Denmark name: Julie Borgen Braget role: CONTACT lat: 56.08481 lon: 12.31803 facility: IHR CRN: Thames Valley and South Midlands status: NOT_YET_RECRUITING city: Oxford country: United Kingdom name: Susan Jebb role: CONTACT lat: 51.75222 lon: -1.25596 hasResults: False