Water & Hydration

Just a few things to discuss:

Kidneys have an ability to work with less fluids depending on intake. If you intake less, the kidneys 'learn' to retain certain electrolytes, like sodium. This does not mean you do not need or can get away with having less fluids, however. I do not recommend stressing the kidneys, and dehydration DOES put stress on the kidneys. "The body has no provision for water storage; therefore the amount of water lost every 24 hours must be replaced to maintain health and body efficiency." [Krause's Food and Nutrition Therapy] On average the kidney will excrete 50 - 60 ml of fluid per hour. Keeping hydrated is essential. The kidneys [healthy ones] don't stop working [thank goodness!] so you shouldn't stop supplying it with the fluid it needs to do it's job.

An important way you know you need to hydrate and give those kidneys work is through the thirst mechanism. The thirst mechanism is not precise at dictating your body's state of hydration. However, your body does not sense thirst until well after dehydration begins [the point where you begin to lose weight due to water loss]. Also, as you age this mechanism becomes less strong. Seniors, for example, may not realize they are thirsty until well after they are showing signs of dehydration.

Percentage of Water in Common Foods:
Lettuce, iceberg --- 96%
Celery -------------- 95%
Cucumbers -------- 95%
Watermelon ------- 92%
Nonfat Milk ------- 91%
Raw carrots -------- 88%
Eggs ---------------- 75%
Beef, sirloin ------- 59%

Percentage of Body Weight Lost
By 1% - Thirst
4% ---- Increased effort for physical work, nausea
6% ---- Failure to regulate excess temperature
10% --- Muscle spasms, delirium, and wakefulness
11% --- Inability of decreased blood volume to circulate normally; failing renal [kidney] function
Between 9 - 12% body weight loss of water can be fatal

At rest in a cool environment your body loses 60% of its water loss through urine. Another 30% is lost through skin and respiration. The other 10% is lost through sweating and feces.

During prolonged exhaustive exercise in a cool environment your body loses 91% of its fluids through sweating. Another 7% is through respiration and the final 2% is through skin and urine.
This water loss change is because the body shuts down the unnecessary systems to perform physical exercise. This is much like the 'Fight or Flight' response. For example, even if you've just finished a meal and are attacked by someone your body will shut down your digestive system to save up energy and prepare for fighting back or running away. Again, this is why during prolonged exercise your body loses almost all of the fluids through sweat rather than through the urine [as a person at rest will].

Enjoy the month of October, and check back soon :)