Let’s discuss the reasoning behind this:
It’s not because water is some magic diet pill or has special powers. Drinking water before a meal makes you feel fuller faster so that you eat less (in reality, with the pre-meal water, you’re not eating less than you should be; you’re just eating just as much as you need). So, you should always drink two glasses of water before a meal. And continue to drink water throughout the meal, too.
Additionally: chew each bite 20 times before swallowing. Your body needs to recognize that it’s eating food and it has to recognize how much it’s eating in proportion to how much it needs. Your body needs time to make these connections; so don’t scour down all your food at once.