A researcher will offer to participate in the study to scheduled for outpatient colonoscopy, who meet all the inclusion criteria and none of the exclusion criteria. The researchers will explain the purpose of the study and will ask to sign the informed consent. They will give verbal and written information on the diet and the bowel cleansing solution to be taken. Thus, according to the allocation group, participants must comply with a low fiber diet the previous day of the examination or 3 days prior to the examination. In both cases, patients will take a liquid diet the night before.