Water truly is the stuff of life. Every cell in our body requires water to perform the necessary functions that keep us going, and without water we would only survive a few days. Our bodies range from about 78% water when we are babies to about 55-60% as adults. And when it comes to answering the question “How much water do I need?” there is no one answer that fits all people.
Generally speaking, the average healthy adult will need about 1 cup of water for every 12.5 pounds of body weight. Someone weighing 125 pounds will therefore need about 10 cups of water or other fluids per day. After accounting for the fluids present in foods, the Institute of Medicine recommends the average adult man aim for 13 cups of additional fluids per day and the average adult woman aim for 9 cups of additional fluids per day. These amounts are needed to replace what is lost from normal body functions such as breathing, perspiration and urination.
If you don’t replace what’s lost you can become dehydrated. Even mild dehydration can impact your mental and physical performance. It can give you a headache, muscle weakness, fatigue or even make you dizzy. Feeling thirsty means you need more fluids, but don’t wait until you feel thirst before drinking. Sometimes the body’s thirst signal doesn’t work properly, especially as we get older. Another way to gauge your hydration is by the color of your urine. It should be light yellow in color. If it is too dark, you should drink more fluids. If it is clear, you’re probably drinking a bit too much.
When You Need More Water
Exercise: During exercise you generate more heat, and, in response, your body sweats to cool itself down. Not being properly hydrated can reduce you body’s ability to sweat and actually make you feel like you are working harder than you really are. The American College of Sports Medicine has developed the following hydration guidelines:
Heat, Winter and Altitude: Drink more fluids in hot, humid weather to replace fluids lost to sweating. Although you might not think about it, in cold weather we lose fluids via our skin moisture from dry indoor heat. High altitudes also increase the need to consume more fluids.
Illness: Fever increases fluid needs. Replacing fluids lost to diarrhea and vomiting are very important and sometimes may require IV fluids if someone cannot consume enough to keep up with their losses.
Alcohol: Alcohol consumption causes the body to lose extra fluids. The awful feeling of a hangover is partly due to the body being dehydrated. To reduce the dehydrating effect of alcohol, make sure you are adequately hydrated before drinking. Alternate alcoholic drinks with other fluids and drink plenty of fluids to re-hydrate yourself before going to bed.
Airplanes: The environment inside an airplane is very dry. Drink plenty of fluids before getting on the plane. Take a bottle of water with you and regularly drink throughout the flight.