My clients love to tell me how much water they drink allll day long. But hold up one minute…did you know that the 8×8 or eight, eight-ounce glasses of water a day is an urban legend right up there with the mall parking lot ankle slasher and the needles in the gas pump scare? Yes, dear readers, you may not need 64 (or more) ounces of H2O a day, at least, not in the form you think of (i.e. straight-up water) when we talk about fluid needs.
So how did this recommendation come about? In a review of the subject by Heinz Valtin, Dartmouth Medical School, it apparently was born from a brief, unreferenced statement by Dr. Frederick Stare in a 1974 nutrition book. Although Stare was a well-respected and oft-quoted nutritionist, according to Valtin no scientific study actually has pinpointed the exact amount of fluid we should be consuming. Of course there has been plenty of research surrounding athletes and fluid needs, but not so much for us average folks. The Dietary Reference Intake report recommends 2.7 liters (91 ounces) of water for women, and 3.7 liters (125 ounces) of water for men. But this is TOTAL water, which includes water from beverages AND foods (and we can estimate about 80% of our daily water comes from fluids, 20% from foods).
Okay, Lisa, you say, why don’t you tell me how much I really need? Alrighty then, here goes: I recommend to my clients about 4-6 eight ounce glasses of plain (i.e. NOT a sweetened beverage like regular soda or juice but can include a diet beverage such as Crystal Light) water each day; this does not include fluids consumed before, during and after a workout. Coffee, tea and diet soda can contribute to overall intake, but plain H2O I believe is a better choice. As the temperature rises outside and your type of physical activity changes and the level increases, I recommend upping your consumption. A good rule of thumb is to weigh yourself before your workout. Then weigh yourself AFTER your workout. For every pound of weight lost drink 16-24 ounces of plain water to replenish those lost fluids.
If working out for under one hour in comfortable conditions (for example, inside a gym), there really is no need to drink water during the workout unless you are an individual who sweats profusely. Sixty minutes or more of vigorous activity, you should begin to take in about eight-ounces of water every 15-30 minutes or so. This fluid may be a glucose electrolyte solution, such as Gatorade. This type of beverage should ONLY be consumed after 60 minutes or more of vigorous activity, otherwise, you’re just taking in needless calories. If working out outside in higher temps you should pay close attention to your fluid needs, especially if participating in strenuous or distance-type activities. Hot, dry skin is your major cue to stop what you are doing, get some water, and find a spot in the shade!