 Part A, will be a single-blind, randomised, placebo controlled, multi-centre, two-period cross-over study. Approximately 24 subjects will be enrolled such that a minimum of 20 subjects complete dosing and critical assessments. All subjects will be required to complete questionnaires, perform a series of behavioural tasks and scanning procedures. Safety and tolerability will be assessed by monitoring subjects for adverse events, vital signs, ECGs, movement disorders EPS, Akathisia and laboratory parameters. The pharmacokinetic profile of the compound in this subject population will be determined by blood sampling over a 72 hour period post dosing, in both sessions. Part B will consist of 12 weeks weight management directed by a dietician on an outpatient basis. Subjects will have fortnightly visits with a dietician and at the end of the 12 weeks complete three questionnaires TFEQ-18R, DBEQ and YBOCS-BE and have their weight measured to assess weight loss. 