A lot of the food we consume is made up of water. What do they use as an explanation for that?
Hydrochloric acid is "hydrophyllic" which basically means that water soluble items are digested more quickly.
Hmmm....have you ever wondered why you need to pee soooooooo quickly after drinking water?
If the water stayed in the stomach (which it doesn't) it would dilute the acid....but this is not the case. It passes straight through into the small intestine where most of it is absorbed.
So what about the gas I hear you ask? Stuff that is not hydrophyllic.....gets digested more slowly (like complex carbs such as starchy vegies) as they take longer to break down. If you eat something that digests slowly followed by something that digests quickly you promote gas production by fermentation of the sugars in the fast-digesting substance (ie: it keeps digesting as it gets stuck behind the other stuff).
For example....you should never eat fruit for dessert after a heavy meal.....BAD, BAD, BAD!!!
So the answer to your question would be it's OK to drink whilst you're eating. Fluid acts as a lubricant to aid swallowing. As for the drinking a glass of water before eating so your stomach fills up and you don't eat as much....well, I'm not sure about that. I'd hate to have to get up to pee in the middle of dinner!
I must say you guys are really testing me with all this anatomy and physiology stuff!!!
Keep the questions coming!