The iPREVENT trial is a randomised, placebo-controlled, double-blind trial to investigate the impact of inulin propionate ester (IPE) on weight gain prevention in adults aged 20 to 40 years at high risk of gaining weight. 270 participants have been randomised to either IPE or inulin control for 12 months. The iPREVENT trial is running at two UK sites; Imperial Clinical Research Facility (CRF) in London - Imperial College Healthcare NHS Trust and Glasgow CRF - NHS Research Scotland.