I’m often asked by patients how much water they needs to drink each day. The Institute of Medicine has calculated that men need about 13 cups or 3 quarts of liquids and women need about 9 cups or 2 quarts of liquids daily. We also ingest approximately 2 ½ cups, or 20% of our daily intake of liquids from food, especially fruits and vegetables. In addition, beverages that we commonly drink such as coffee, juice, milk and soda are composed mostly of water.
Water makes up 60% of our body weight. Every cell and system of our body depends on water. Lack of water causes dehydration, a condition that occurs when the body receives an inadequate amount of fluids, which in turn slows down and eventually shuts down vital bodily functions.
Our bodies constantly lose water from perspiring, breathing, urinating, and having bowel movements.
Various factors determine just how much more water we may need to drink, such as:
- Environment – Hot weather, especially with high humidity, increases perspiration. Even in frigid weather, water is lost from our bodies when breathing during activities such as skiing or hiking.
- Exercise –Also increases perspiration. The more prolonged and intense the exercising the greater the fluid loss.
- Illness – Intense or prolonged vomiting and/or diarrhea can lead to life threatening dehydration. This is an unfortunate cause of death in many developing countries.
- Pregnancy and breast feeding – Increases women’s fluids needs.
After hours of prolonged exercise with heavy sweating we lose electrolytes, especially salt. This is when drinking a sports drink is recommended because it will not only replace the lost water but also the depleted electrolytes. Electrolytes lost through sweat from mild to moderate exercise, can be replaced from the food we eat.
Some liquids can act as a diuretic, which means they cause you to urinate more liquid than you’ve taken in. Caffeine is often implicated, but is really a weak diuretic. Alcoholic beverages on the other hand, especially at higher quantities, can be very potent diuretics causing dehydration which is a major cause of a hangover.
A rough guide as to whether or not you are consuming enough water is to check your urine color. If it appears light yellow, like lemonade, you’re probably well hydrated and if it is very dark yellow, like apple juice, you need to drink more water.
To keep your body healthy:
- Drink a glass of water or other low or non-calorie beverage with each meal and between each meal.
- Drink water before, during and after exercise.
- Or, do what makes sense and just follow the simple common advice to drink water when you’re thirsty.
- Terry Hollenbeck, M.D., is a retired urgent care physican at Palo Alto Medical Foundation Santa Cruz in Scotts Valley. Readers can view previous columns on his website, valleydoctor.wordpress.com, or e-mail th*************@gm***.com.
