If you are having a colonoscopy the next day, you can have dinner the day before, but it is recommended to have a light liquid or semi-liquid diet, and you need to fast for at least eight hours before the colonoscopy. Before colonoscopy, it is recommended to fast for at least eight hours, and for those with poor digestive function and weakened gastrointestinal emptying ability, it is recommended to fast for a longer period of time. Therefore, you can eat the night before the colonoscopy, but it is not recommended to eat too late, which will affect the next day’s examination; diet is recommended to be easy to digest and excrete fluid or semi-fluid diet, avoiding spicy stimulation and other foods that cause gastrointestinal function abnormalities, which will affect the results of the examination. It should be noted that for the old and weak, if dizziness, sweating and other symptoms occur after a long period of time without food, it can be appropriate to contain fruits and sugar and other foods to replenish physical strength. After the colonoscopy, pay attention to tracking the results of the examination, and if abnormal results occur, consult a doctor in time.