There are several opinions on drinking during and after meals. Some traditional and alternative health experts say, that drinking water during meals or immediately after is very unhealthy, apparently you have to wait for at least 2 hours and only then have a drink.
They say that water dilutes the digestive juices in the stomach, and when the concentration of stomach acid and enzymes is low, food doesn't digest as well.
They also say that water dilutes food and washes it down and out of stomach too quickly.
There is some truth in this statement, but the mechanisms described by these "experts" are completely different.
First of all, let me reassure you, that drinking during and after a meal is TOTALLY FINE.
Your stomach is not just a sack of skin where all the food is mixed and sent down the gut, it is well designed and very "clever". It has special creases or folds from the top where food comes in from the gullet (oesophagus) to the bottom of the stomach where it opens further down (into the duodenum).
When you drink water it runs down these creases down and out of the stomach, often without touching food and without mixing with stomach juices at all.
That's why it doesn't matter when you drink - before, after or during the meal, unless, of course you drink a pint or two at a time.
If drinks could disturb the digestion process, then soups would be harmful to your system too.
But a lot of people eat soups regulary and have perfect digestion.
So you can safely drink when you like - after, during and before the meal. BUT!
And this is a big BUT!
Let me give you a quick introduction first. In 1969, a well known scientist and rentgenologist professor V.D.Lindenbraten was doing some research involving stomach and gut rentgenology. He was trying to retain contrasting substances in the stomach of the patient long enough to have sufficient time for a full x-ray investigation. (If you are new to rentgenology, it is the science of taking and interpreting X-rays, today it is called Radiology. The contrast substances can be added to the stomach or gut to be able to see its shape and other qualities on the X-ray).
Professor L. found that a contrast substance (chalky porridge-like drink) when given cold from the fridge would leave the stomach more quickly, than the time needed to tune-up the X-ray machine, not leaving any time for X-rays to be taken. However, if the contrast was warmed up before it was given to the patient, there was enough time to tune everything up and do a full X-ray investigation.
The professor and his colleagues were very excited about this fact and conducted some further research. The results have shown, that drinking cold drinks like cold water or Cola with ice during or after the meal shortens the time that food stays in the stomach from 4-5 hours to 20 minutes. Basically, when you drink cold water - the food you have just eaten is "pushed out" of the stomach.
There are two problems with this: first of all, you put on weight more quickly, because there is not enough time for proper digestion, therefore you get NO good nutrients, however, simple sugars and fats don't need much time to be digested, so you get those and nothing else. You will feel hungry almost immediately, because your boody still needs the nutrients you are missing. The second problem is that when food is not digested properly in the stomach, it will literally rot in the gut, producing various poisons causing bloating, diarrhea, constipation, skin conditions and other health problems.
This is how McDonalds and other fast food chains make their fortune! Your body nutritional requirements will never be satisfied with fast food if you keep washing it down with icy drinks, meaning, that you will eat more and more... You have probably noticed, that hot drinks are not included in set meals and are never advertised. This is in contrast with cheap Cola which is agressively advertised. And not just Cola, but all cold drinks.
The stomach prepares proteins in your food for further proper digestion and absorbtion. Therefore, if you drink a cold drink after food, the protein part of the meal will go down unprepared for digestion, it will never be split into amino-acids and will be rotting in your gut for hours and if you tend to get constipated, it will rot there for days. Undigested protein will rot very quickly at a temperature of 37 degress (your body's temperature).
Money paid for this food will be wasted of course, and instead of the goodness of the nutrients your body is desperate for, you might get a number of gut inflammatory conditions (enteritis, colitis) and disbacteriosis (absence of benefitial bacteria in your gut which must aid digestion and health).
By the way the same advice is valid for after a meal - ice-cream too acts on your digestion in a similar way.
Drinking water should be at least room temperature and when you drink after a meal, please warm it up to at least 37 degrees.