You need to have a non-residue diet 1 day before the colonoscopy, and foods such as bread, buns and noodles are fine foods that are easy to digest and have little food residue. The so-called non-residue diet is to avoid the intake of coarse fiber foods, such as common vegetables, fruits, meats and nuts. This type of food can lead to incomplete emptying of the intestines, and some subtle lesions may be covered by food debris, resulting in inaccurate colonoscopy results. Laxatives are also needed to empty the bowel before the colonoscopy, during which you need to drink plenty of water to avoid dehydration and electrolyte disorders. The choice of laxatives and precautions should be directed by your doctor. For the diet before colonoscopy, it is recommended to be instructed by the doctor. Avoid leakage and misdiagnosis due to inadequate bowel preparation.