Visit 4: The subject will give the study coordinator their 3-day food diary, the daily and weekly IBS symptom diary, and any excess fiber product. The physician will review their IBS symptom diary and ensure there are no significant adverse events. The physician will complete a physical exam and take their vitals (such as weight, waist circumference and blood pressure). The subject will then be asked to fill out a series of questionnaires relating to their diet (VioScreen Food Frequency Questionnaire), IBS symptoms (IBS-Quality of Life questionnaire (IBS-QoL) and IBS Questionnaire by Whorwell and Francis), sleeping/circadian patterns (2 NIH sleep questionnaires, Munich Chronotype Questionnaire, Lark/Hummingbird/Owl questionnaire, food timing questionnaire), the Expectancy and Credibility Questionnaire, and the 34-item tool asking about their GI symptoms and severity. They will then have 2½ tablespoons of blood drawn by a certified nurse or medical assistant. Subjects will be reminded in advance to fast 12 hours prior to their research visit. The blood tests include: CBC, CMP, CRP, TSH, INR, fasting lipid profile and HbA1c. Among these blood tests, the fasting lipid profile results will be given to the subject after the completion of the study. The rest of the results will be given to the subject at their next visit. They will be provided with a 3-day food diary and a daily and weekly IBS symptom diary to fill out prior to Visit 5. Visit 4 will be about 3 hours in length. The next visit will be 4 weeks after their fourth visit, which is the subjects' last visit.