Patients will be seen on weeks0, 2, 6, 8, 12 and during week 20. Week 6 will be only a dietitian visit. The last visit is a visit off diet to evaluate sustainability of the initial intervention, safety and changes in BMI due to FT or diet. A telephone conversation to assess SCCAI will be made at week 1 and week 7. At each visit (weeks 0, 2, 6, 8, 12, 20) patients will have Weight, a disease activity score, PGA, CBC, CRP, albumin and complete chemistry panel performed. Adverse events and medications used will be recorded at each visit.Stool samples for microbiome (16S rDNA, Short chain fatty acid analysis) and Calprotectin will be measured locally at baseline, weeks 2, 8 and 12. All patients (patients in group 1,2 and 3) will have a repeat sigmoidoscopy performed at week 8. A food frequency questionnaire will be performed on week 0 and a food diary will be collected at week 2 and 12. A compliance questionnaire will be completed on weeks 2, 8and 12. A 24 hours recall will be collected at weeks 0, 2 and 6.