Drinking while eating dilutes gastric juices and impedes digestion. In fact, drinking might cut your appetite, nothing more. During digestion, the stomach secretes an acidic mix (gastric juices), the enzymes needed to properly digest food. In order to maintain a good level of acidity, the stomach adjusts the production of these juices based on the amount of food consumed and the consistency of the meal. If there is more liquid, the stomach will simply secrete more gastric juices.
Is it true you should not drink during a meal?