Eating late at night the next day edema may be caused by drinking too much water, or consider is due to nephrotic syndrome, right heart failure and other diseases. 1. Drinking too much water: As the human body has a certain function of maintaining water balance, when the night to eat late-night snacks lead to excessive water intake, part of the water has not been discharged through the kidneys, so the next day part of the people may appear edema. This kind of situation is a normal phenomenon, generally do not need to worry too much. 2. Nephrotic syndrome: The cause of nephrotic syndrome is related to immunity, heredity, drugs, infection and other factors. Patients will have edema, weight gain and other symptoms, which can be manifested as edema the next day after eating a snack at night. 3. Right heart failure: The causes of right heart failure include myocarditis, diabetes mellitus, and cardiac overload. Symptoms are bloating, abdominal pain, edema, nausea, vomiting, etc. Some patients experience worsening edema the next day after eating a late-night snack. If the symptoms of edema are not relieved, patients are advised to promptly identify the cause and follow medical advice.