Dehydration occurs when too little water or fluids are consumed. Symptoms include feeling tired, weak, dizzy, and head achy. Energy levels decrease as does stamina for any activity you may try to perform.
Over the years, there have been all sorts of recommendations about how much water we should be consuming including formulas that make you calculate what you need---something like an ounce for every pound you weigh times some number, divided by something else. Ya, right. Just ignore these formulas, since individual needs vary too much and can be influenced by health, activity and even where that person is living.
The National Academy of Sciences, Foods and Nutrition Board recommends that men consume about 13 cups of fluid each day, and women should get 9 cups. These recommendations include total fluid intake not just water: milk, juices, tea, coffee, alcohol, and even the water in foods contribute to fluid needs. Food actually provides about 20% of daily fluid needs. Some fruits supply more than others, as watermelon and tomatoes are 90% water!
The daily 8 glasses of fluids each day is supported by this calculation:
The average adult produce 1.5 liters of urine each day,
and 1.0 liter is lost in breath, sweat and bowel function
which equals 2.5 liters lost daily
Food provides 20% of water = 0.5 liter taken in
that leaves fluid needs of 2.0 liters, or 8 cups
for a total of 2.5 liters
But, who is that average individual? Some experts still recommend the guide of 8-8 oz of fluid each day; it's easy way to remember to drink fluids, but it's really not supported by scientific evidence.
An individual's needs have to be considered. Acute illness (fever, diarrhea, vomiting, bladder or urinary tract infection,) living at higher altitudes (over 8200 feet) or in hot, humid, or heated environments, Increase the body's water needs. Exercising certainly increases the need for fluids, and is influenced by the intensity and duration of activity. Even he health and age of a person alter fluid needs.
The Mayo Clinic recommends that we have one glass of water with each meal and between each meal. I like this idea as a starting point, as it's quite simple. Other experts recommend drinking enough fluids to rarely feel thirsty. The problem with that is that as people get older, their ability to sense thirst diminishes.
One of the best rules of thumb is to drink plenty of fluids throughout the day, keeping thirst at bay and to keep your urine clear or very pale yellow. How about: Be sure to see paler pee? When urine is dark yellow or gold colored dehydration is often present. Not good for any cell in your body.
Water is a great choice to drink. It's what every cell in your body really wants and needs. The big bonus is that it's inexpensive and calorie free.
Stay tuned for Part II, where we'll talk about how exercise changes your fluid requirements and how to choose the best fluids for exercise performance and recovery. In Part III, we'll investigate whether or not water helps with weight loss.