It is not recommended to eat celery that has been cooked overnight if it has not been placed in the refrigerator. Fresh celery can be eaten if left overnight. If cooked celery is not kept in the refrigerator overnight, the amount of bacteria in the celery will increase. Many pathogenic bacteria can multiply in the celery, which may cause gastrointestinal discomfort after consumption. Especially for patients with a weak constitution, it may cause more harm to the body after consumption. However, fresh celery can be consumed overnight without loss of nutrients. Try to choose fresh celery for cooking before consumption. It is recommended to consume less leftovers on a daily basis, especially overnight meals. If you need to eat them, they should be stored in the refrigerator for at least a reasonable amount of time.