Our bodies use water to perform a variety of essential functions, including regulating body temperature, lubricating joints, protecting organs, flushing waste and carrying nutrients and oxygen to the cells while also dissolving other minerals and nutrients. If you do not replenish your body’s supply of water by drinking fluids, you can become dehydrated. So what is dehydration? It is when the fluid loss from our body (which is at least 60% water) is not replaced by fluid intake. Dehydration may affect your body’s ability to perform normal functions such as concentrating or recalling information.
It occurs at all ages, but dehydration is most common in babies and older adults. It occurs more frequently as temperatures rise in the summer months, but it can occur throughout all seasons. It is easy to treat if an individual knows the symptoms.
Dehydration in babies is typically the result of vomiting and diarrhea and, surprisingly, the only way to diagnose it is to see if the baby is crying but not shedding tears.
In older adults, dehydration can be due to limited physical activity or no easy access to water. Also, it may be a secondary effect of medications such as diuretics to control hypertension, which cause excess urination and, strangely, is not always associated with thirst. Other symptoms may include a dry mouth, lips and tongue, less urine, dark-colored urine (usually yellow), lightheadedness, dizziness, tiredness or fatigue. It can also be related to strokes.
Symptoms also include muscle cramps, irritability and usually thirst. Another sign is dry skin, which I have tested over the years when I feel I am getting dehydrated. Not only do I look at urine color, but I have a simple skin test I use. With my right-hand thumb and index finger, I try to pull some skin on the top of my left hand and see if it retracts immediately. If it remains in the pinched position, I know I am dehydrated and I then try to increase my water intake. Another early symptom of dehydration is dry eyes. This is occasionally accompanied with floaters, blurred vision, sensation of a foreign body in the eye, redness, stinging or burning.
Research is limited on how hydration affects human cognitive function, but brain function, as well as short-term memory and attention, is most likely affected by dehydration and a loss of sodium and electrolytes. Also, it is known that if a person is in the early stages of dementia, dehydration may accelerate that decline.
Prolonged dehydration is a medical emergency. Even though you can survive for up to three days without any water consumption, hydration should be pursued long before that if possible.
If you have a problem with dehydration due to one of the above reasons, or perhaps from sweating due to exercise or exposure to summer heat, follow these guidelines for making corrections.
To calculate how much water you need, divide your weight in pounds by two to obtain the ounces of water you should consume daily. For example, if you weigh 200 pounds and you divide that by 2, that means you need 100 ounces of water daily. A person weighing 120 pounds would need 60 ounces per day.
But what is another way to correctly hydrate? Be mindful that other beverages can contribute to the daily fluid intake, although the gold standard is the consumption of plain water. To accomplish this, I keep a large container of ice water on my desk and try to consume about 30 ounces of it per day. Also, fresh fruit is a source of water. Watermelon and oranges are great options. Surprisingly, the vegetables with the highest water content (96%) are iceberg lettuce and cucumbers. Tomatoes are 95% water, spinach 93%, mushrooms 92%, and broccoli is 90%.
As I reviewed this list of vegetables and fruits, it again reminds me of one of the most important of our “8 Steps to Get Cooperized,” which is “five is fine, nine is divine,” referring to the number of fruits and vegetables combined you should be consuming daily. Fruit and vegetable intake is an ideal way to rehydrate, plus they contain additional vitamins and have other essential benefits. I am not recommending that you become a vegetarian strictly for controlling dehydration, but keep in mind that this is one way to help correct the problem.
Finally, I also try to drink at least two 8-ounce glasses of skim milk daily for its water and protein content. I am sure that these habits to “Get Cooperized” are the major reasons I am still functioning normally—working daily, starting the day with prayer and Bible study and ending the day with an hour of aerobic and muscle training activity at Cooper Fitness Center before going home and walking the dogs for at least 15 minutes before dinner.
To enjoy life to the fullest as I have been able to do, pursue both physical and spiritual fitness, and try to embrace the Bible verse that tells us to “glorify God in your body and in your spirit” (1 Corinthians 6:20). ©2025 Kenneth H. Cooper
Kenneth H. Cooper, M.D., MPH, known worldwide as “the father of aerobics,” is the founder and chairman of Cooper Aerobics in Dallas and chairman emeritus of The Kenneth H. Cooper Institute.
The Scripture quotation is taken from The Holy Bible, New King James Version.