AbstractObjectiveTo evaluate the first phase of a specialist weight management programme provided entirely within the UK National Health Service.DesignProspective cohort study using multiple logistic regression analysis to report odds of ≥5 kg weight loss in all referrals and completers, and odds of completion, with 95 % confidence intervals. Anxiety and depression ‘caseness’ were measured by the Hospital Anxiety and Depression Scale.SettingGlasgow and Clyde Weight Management Service (GCWMS) is a specialist multidisciplinary service, with clinical psychology support, for patients with BMI ≥35 kg/m2 or BMI ≥30 kg/m2 with co-morbidities.SubjectsAll patients referred to GCWMS between 2004 and 2006.ResultsOf 2976 patients referred to GCWMS, 2156 (72·4 %) opted into the service and 809 completed phase 1. Among 809 completers, 35·5 % (n 287) lost ≥5 kg. Age ≥40 years, male sex (OR = 1·39, 95 % CI 1·05, 1·82), BMI ≥ 50 kg/m2 (OR = 1·70, 95 % CI 1·14, 2·54) and depression (OR = 1·81, 95 % CI 1·35, 2·44) increased the likelihood of losing ≥5 kg. Diabetes mellitus (OR = 0·55, 95 % CI 0·38, 0·81) and socio-economic deprivation were associated with poorer outcomes. Success in patients aged ≥40 years and with BMI ≥50 kg/m2 was associated with higher completion rates of the programme. Patients from the most deprived areas were less likely to lose ≥5 kg because of non-completion of the programme.ConclusionsFurther improvements in overall effectiveness might be achieved through targeting improvements in appropriateness of referrals, retention and effective interventions at specific populations of patients.