Recently, I was lucky enough to sit in on a lecture from Lawrence Armstrong, Ph.D. FACSM an expert in the area of hydration. It seems like a lot of health specialists give out the advice to drink more water, and we all remember the campaign for 8 glasses of water a day. But how much water do we need to be drinking on a daily basis and why is it so important? Dr. Armstrong had some excellent answers and his current research is even more compelling and persuasive in my own effort to remain properly hydrated.

Dr. Armstrong was surprised when he asked if the people at the lecture knew their sweat rate and very few hands went up. Sweat rate? Well, how much water you lose during a typical work out tells you how much water you will need to remain hydrated. The homework he gave us was to do a simple test. Weigh yourself naked right before going to the gym. Work out for an hour without consuming water if possible (or keeping track of the ounces of water consumed). Weigh yourself naked again when you get home. The difference in weight in pounds can easily be converted to the ounces you will need to replenish. Everyone has a unique sweat rate but Runner’s World recruited some running subjects to give their readers an estimate. For a woman weighing 140 lbs., they estimated 4.6 oz./mile should be consumed if environment is about 70 degrees Fahrenheit.

The most surprising fact to me about hydration? If you are thirsty, you are already dehydrated. This is incentive to keep a bottle of water with me at all times. It might be minimal (1-2%), and can be easily corrected by drinking a few ounces of water, but Dr. Armstrong’s most recent studies have shown effects from these small amounts of dehydration can range from irritable mood to impaired cognitive performance. Interestingly, women were much more effected in the “mood” department with mild dehydration and the study took strict measures to make sure they were isolating hydration level effects and not those due to hormonal changes.  In the 2012 study, Mild Dehydration Affects Mood in Young Healthy Women, the authors concluded “degraded mood, increased perception of task difficulty, lower concentration, and headache symptoms resulted from 1.36% dehydration in females.” And that “increased emphasis on optimal hydration is warranted, especially during and after moderate exercise.”

To help you find out the ideal amount of water you should be drinking you can take a look at this hydration calculator. It will take into account your age, weight, physical activity level and estimate how much water you are getting from food and beverages based on your daily routine to determine if you are consuming enough .

Lastly, a good measure of your hydration is your pee. Contrary to many people’s perceptions, it is actually very rare to have clear urine. Most people when hydrated produce urine that is pale yellow. Here is a link to Dr. Armstrong’s urine chart, enjoy!