Originally Posted by quince
i'm afraid coffee doesn't count as it is a diuretic, so it actually makes you excrete fluid more.
This actually is a myth, and one that contributed to my mother being hospitalized for water poisoning also called water intoxication (essentially water overdose).
The kidney specialist called in on her case busted several of the popular dieting water myths and told us he's seeing water poisoning in healthier people. It's still rare, but it was once almost always only seen in marathon runners and other extreme athletes, mentally ill folk with water drinking compulsions, and people (mostly young men) trying to wash drugs out of their system for a drug screen.
Myth #1: Coffee, beer, and wine are dehydrating and need to be compensated for with extra water.
He pointed out that if coffee drinking were as dehydrating as people claim, that people who drink only coffee would die of dehydration (that's a lot of people, and they don't).
Even most alcoholic beverages, unless you're drinking high-proof shots, aren't dehydrating enough to result in a fluid deficit. 8 ounces of water may provide a little more fluid than 8 ounces of coffee, but coffee still contributes to your fluid intake, and it actually comes pretty close.
Myth #2: A person needs 1/2 ounce of water for every pound of body weight.
This is also false. The formula is safe for average weight folk, but an obese person's water needs are not that much greater than an average person's. For morbidly obese folk, this myth can be quite dangerous, especially if they happen to also be on blood pressure meds or diuretics.
Myth #3: Only water counts.
Everything counts. Even the water in the food you eat. It's even possible (if you ate enough water containing fruits and vegetables, and most people don't) to satisfy all of your fluid requirements in food.
While my mother was in the hospital, she was on strict water restriction, and even the moisture in her food was counted.
Myth #4: Only pure water counts, it's easiest for the body to process, and all other beverages "confuse" the body.
Nope, this isn't true either. The human body processes water just fine if the water has stuff in it. And, in fact, drinking water always has stuff in it. Pure water is distilled water, and distilled water isn't recommended for drinking water, because it could, over time, pull minerals from your body through osmosis.
Myth #5: Thirst is not a reliable indicator of water needs. By the time you're thirsty, you're actually dehydrated.
This also is a myth. For most people, thirst is the best and only necessary indicator and measure of fluid needs. There's no factual basis for the myth that hunger is easily mistaken for thirst. Drinking fluids may reduce your appetite (for a very short time, because the stomach empties fluids far, far quicker than food), but in most cases thirst is your best indication of thirst.