 [ Symptoms ] my daughters got their flu shots today how long does it take until the flu shot is effective [ Disease ] doctors and dietitians encourage patients to keep a food and symptoms diary for several weeks by keeping track of what you eat and how you feel afterward you can identify specific foods that exacerbate your symptoms  says dietitian tracie dalessandro rd author of what to eat with ibd a dietitian may also want to review your diary to make sure that you are eating a well balanced diet that includes all the nutrition you need many experts recommend keeping a diary for at least three weeks keep in mind that your goal should be to eat as wide a variety of foods as you can to assure well balanced nutrition diets that eliminate many foods are hard to follow and may result in nutrient deficiencies  says dalessandro