Obesity is a major public and personal global health issue. A major clinical issue in managing the obese individual is the prevention of weight regain following successful weight loss initiatives. There has been recent interest in the role of the central neurotransmitter dopamine on appetite control and energy balance, and several small studies have suggested that dopamine agonist medication could be a novel way to treat obesity. This randomised controlled trial will identify if the dopamine agonist drug Cabergoline is effective at preventing weight regain: 200 obese people will be included in the trial and followed for 2 years. If Cabergoline is successful at preventing weight regain, it could have a major impact on how obesity is managed and could open up an new area of future research for this class of medication.