8 glasses – that’s what most people think they need as a daily requirement.
Copious water intake is supposed to keep organs functioning properly, skin supple and body weight at bay.
Say researchers from the University of Pennsylvania who conducted a study to test these theories (which will be published in the June issue of the Journal of the American Society of Nephrology).
We all know that our bodies need water, but nobody quite knows exactly how much. Let’s take a look at where this misconception began, shed some light on water and hydration and look at some more realistic water goals.
Let’s be clear on something right out of the shoot. Water is the hub of all chemical processes in the body and the king of all nutrients. We should be drinking it daily.
Where did the 8 glasses/day gospel originate?
Dr. Frederick Stare suggested this theory in a book “Nutrition for Good Health” published in 1974 (“theory” being the operative word). The theory caught on despite its arbitrary origins and it has been speculated that bottled water companies are largely responsible for perpetuating the 8-a-day mantra.
Water Intake – Not Just From Water
Counter to what I’ve just presented, we actually DO need at LEAST 8 glasses of water per day.
But here’s the catch: This intake is satisfied not only from water intake, but also from other fluids, the food we eat and the metabolic processes required to break down that food.
Juice and milk contribute to hydration and (surprisingly enough) so do caffeinated and alcoholic beverages. I probably don’t have to tell you though, that alcoholic beverages are not recommended to help you meet your fluid requirements.
Regarding caffeine – many people still believe it causes dehydration, however studies as early as 1928 have shown otherwise.
The fluid from food and its accompanying metabolic action alone can account for as much as 6 glasses of water! Water is the best fluid – no argument there, but don’t get caught up in the absurdity of forcing down extra glasses of water if you have a coffee.
Water – Too Much of a Good Thing?
The more the better does not apply to even the mighty water. Consider that 31 runners in the 2000 Houston Marathon were treated for hyponatremia – a condition that can arise with excess fluid consumption, causing a dilution of sodium in the blood.
This has prompted a revision of previous guidelines which have changed from “drink as much as you can tolerate” to “drink as needed, but do not exceed 800ml per hour”
Estimating Water Needs
- There is a large variation when it comes to individual water needs. Those who are active have increased water requirements, especially if exercising in hot weather.
- As a baseline, 1L of water a day (about 3 glasses) should be fine for those individuals who are relatively sedentary.
- Increasing water intake to 1.5-2.5L/day (4-5 glasses) per day is a good idea if you are moderately to highly active, and drink a few gulps every 15-30 minutes if exercising in hot weather.
- If you are exercising for longer periods of time (going on a long hike, as an example), be sure to consume some salt when consuming large quantities of water.
- If fat loss is your goal, make water your primary beverage – aim for 75% of your fluid consumption, while cutting back on juice, pop and other calorie-containing liquids.
Let’s face it, most of us would probably benefit by drinking more water for the simple fact that it replaces other caloric and otherwise unhelpful fluids.
Drink water whenever you can – try to have a glass with each meal, and consume it while you are exercising. Use common sense when hydrating during exercising – especially in hot weather.
You need not, however count empty bottles, or stress if you fall a glass or two short of your daily “requirement”.
How much water do you drink?
- Stare, FJ, and McWilliams M. Nutrition for Good Health. Fullerton, CA: Plycon, 1974, p. 175
- Grandjean, AC, Reimers KJ, Bannick KE, and Haven MC. The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration. J Am Coll Nutr 19: 591-600, 2000.
- Tufts University Health and Nutrition Letter. New Consumption Guidelines for Water Sodium, Potassium. April, 2004
- THE PHYSICIAN AND SPORTSMEDICINE – VOL 31 – NO. 7 – JULY 2003. New Hydration Recommendations.
- Casa DJ: Proper hydration for distance running: identifying individual fluid needs. Available at http://www.usatf.org.
- Weinberg, A, and Minaker K. Council of Scientific Affairs, American Medical Association: dehydration evaluation and management in older adults. JAMA 274: 1552-1556, 1995