Archive for October, 2017

How Much Water Do You Really Need To Drink?

October 28, 2017

Andrew Siegel MD   10/28/17


Thank you Pixabay for above image

Many sources of information (mostly non-medical and of dubious reliability) dogmatically assert that humans need 8-12 glasses of water daily to stay hydrated and thrive. Today’s entry addresses the question of how much water you really need to drink in order to stay healthy.

Fact: Many take the 8-12 glass/day rule literally and as a result end up in urologists’ offices complaining of urinary urgency, frequency and often leakage. Clearly, the 8-12 rule is not appropriate for everyone! The truth of the matter is that although some urinary issues are brought on or worsened by insufficient fluid intake, including kidney stones and urinary infections, other urinary woes are brought on or worsened by excessive fluid intake, including the aforementioned “overactive bladder” symptoms.

Fact: Many foods have high water content and can be a significant source of water intake. In general, the healthier the diet (the more the fruit and veggie intake) the higher amount of dietary water.  For example, melons, citrus fruit, peaches, strawberries and raspberries are about 90% water, with most fruits over 80% water.  The same holds true for vegetables, with lettuce, tomatoes, cucumbers, celery, radishes and zucchini comprised of about 95% of water, with most veggies over 85% water.

Water is a vitally important component of our bodies, promoting optimal organ and cellular functioning, temperature regulation, nutrient and waste transportation, joint lubrication,  and facilitating the thousands of chemical reactions occurring within our bodies. 60% of our body weight is water, two-thirds of which is within our cells and one-third of which is in blood and tissues between cells. For a 165 lb. man, that translates to 100 lb. of water weight. For a 125 lb. woman, that translates to 75 lb. of water weight.

Our body needs water “equilibrium,” with water intake balancing water losses.  Most people need a total of 65-80 ounces daily, although this can vary greatly depending upon one’s size, the ambient temperature and level of physical activity.  Again, water intake comes from beverages and foods consumed, with many foods containing a great deal of water, particularly fruits and vegetables as mentioned, so the 65-80 ounces includes this source. Water losses are “sensible,” consisting of water in the urine and stool, and “insensible,” from skin (evaporation and sweating) and lungs (moisture exhaled).

The formula that doctors use for figuring out daily fluid requirements—especially useful for hospitalized patients not eating or drinking who depend totally on intravenous fluids—is 1500cc (50 ounces) for the first 20 kg (44 lb.) of weight, and an additional 200cc (7 ounces) for each additional 10 kg (22 lb.) of weight.  So, for a 125 lb. woman the daily fluid requirement is 2250 cc (75 ounces).  For a 165 lb. man, the daily requirement is 2600 cc (87 ounces).  It is important to understand that the 75 ounces of fluid requirement for the woman and the 87 ounce fluid requirement for the man in this example includes both beverages and food. If one has a very healthy diet with lots of fruits and vegetables, there will obviously be less need for drinking water and other beverages.

Fact: Caffeinated beverages (coffee, tea, colas, many energy and sports drinks and other sodas) as well as alcohol both have diuretic effects, causing you to urinate more volume than you take in. So, if you consume caffeine or alcohol, you will end up needing additional hydration to maintain equilibrium.

The other important factors with respect to water needs are ambient temperature and activity level. If you are reading or doing other sedentary activities in a cool room, your water requirements are significantly less than someone exercising vigorously in 90-degree temperatures.

Humans are extraordinarily sophisticated and well-engineered “machines.”  Your body lets you know when you are hungry, ill, sleepy and thirsty.  Paying attention to your thirst is one of the best ways of maintaining good hydration status.  Another great method is to pay attention to your urine color.  Depending on your hydration status, urine color can vary from deep amber to as clear as water.  If your urine is dark amber, you need to drink more as a lighter color is ideal and indicative of satisfactory hydration.

Some advantages of staying well-hydrated:

  • Avoids dehydration and all its consequences (this is pretty obvious)
  • Dilution of urine helps prevent kidney stones
  • Dilution of urine helps prevent urinary infections
  • Helps bowel regularity
  • Maintains hydrated and supple, less wrinkled skin
  • Helps keep weight down because of the filling effect of drinking; also, thirst can be confused with hunger and some people end up eating when they should be hydrating


  • Makes you urinate a lot, which is not good for those with overactive bladder symptoms

Wishing you the best of health,

2014-04-23 20:16:29

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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery.  He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community.

Dr. Siegel has authored the following books that are available on Amazon, iBooks, Nook and Kobo:

 MALE PELVIC FITNESS: Optimizing Sexual & Urinary Health

THE KEGEL FIX: Recharging Female Pelvic, Sexual and Urinary Health 

PROMISCUOUS EATING: Understanding and Ending Our Self-Destructive Relationship with Food


These books are written for educated and discerning men and women who care about health, well-being, fitness and nutrition and enjoy feeling confident and strong.