An 8-week exclusive liquid diet (EEN) without any normal food is the best treatment for paediatric CD. The mode of action of EEN remains unknown, but according to recent publications, the modulation of the gut bacteria drives its therapeutic properties. While successful, EEN is a challenging therapy to follow. Half of the paediatric EEN patients will require a nasogastric tube to support treatment, its use in adults is limited, and the need for a more palatable diet is very well described. Based on these findings, a non-liquid and more acceptable dietary treatment was recently devised called CD-TREAT (Crohn's Disease TReatment-with-EATing) diet. CD-TREAT, which is a solid food-based diet designed to replicate the nutrients and food ingredients composition of EEN, was recently tested in healthy adults and a rat model of colitis. In order to pilot CD-TREAT diet as a CD induction treatment, 10 children and 10 adults with active luminal CD will be recruited. Once consented, baseline blood, urine and faecal samples will be collected and the CD-TREAT prescribed for a maximum of 12 weeks. Another 3 blood, urine and faecal samples will be requested during the 12 weeks. All the foods/meals of the CD-TREAT diet will be purchased and delivered to the participants' house by the researcher and the meals which need cooking will be pre-prepared by a sub-contracted catering company. Blood and faecal inflammatory biomarkers will be measured, the disease activity assessed with routinely used clinical indices and the faecal bacteria and its metabolites characterised.