Water: How Much Do We Need?
Water constitutes 50 to 70% of the human body, for the average sized adult that means about 10 gallons, or 40 liters! It serves as a medium for chemical reactions, temperature regulation, transport for soluble nutrients, remove waste products, and lubrication. Muscle tissue contains about 73% water. An average adult can survive up to 8 weeks without eating food, but only a few days without drinking water. This is because there is no storage site for water.
How much do we need?
The average person needs about a milliliter of water for every calorie burned. That works out to be about eight 8 ounce glasses (64oz) per day for a person who eats a 2,000 calorie a day diet. This number changes in regards to diet, environment, and activity.
Water in your Diet
If you eat a lot of fruits and vegetables, which are mostly water, you may not need to drink as much water as someone who eats a lot of meats or breads.
On a comfortable day you lose about four pints of water a day through the skin, as sweat, the moist air you exhale, and urine. When it is hot out you lose more.
Effect of Activity
As your activity level increases your water need increases. If you exercise in the heat of summer you can lose up a quart of water per hour! If you exercise in the heat a good rule of thumb is to weigh yourself before and after exercise. The amount of weight lost is water and needs to be replaced by drinking 8-12 ounces every 15 minutes until the weight is replaced. The time interval is important to avoid over-hydration, which is just as dangerous as dehydration.
This does not count as part of the 64oz of water per day. Imagine pouring seven to nine teaspoons of sugar onto cereal in the morning. Sound too sweet? That is how much sugar is in a twelve ounce can of Coca-cola, Pepsi and other carbonated beverages! Soda is chock full of calories and has zero nutrient value. Not to mention the strain it places on your pancreas to pump out insulin from the high sugar spike in your blood stream. This can lead to diabetes and when the body begins to have trouble dealing with the sugar it raises your triglycerides (bad cholesterol) and increases your chances for developing heart disease. Add the above information to the fact that the phosphoric acid in soda actually causes dehydration, by drinking soda you are putting yourself at an overall water deficit
But I know someone is asking…What about calorie free soda?
This can actually be worse for you. Many of the sweeteners used in these are chemicals that have no place in the human body. Some are carcinogens and others are neurotoxins which over time can place an incredible strain on your nervous system and immune system.
So the moral of the story is: don’t drink soda, of any kind!
Juice sounds healthy, but this is deceiving. Unless the bottle states “Not from concentrate” you are just drinking sugar with water. Have you ever tried real cranberry juice? It tastes nothing like what you buy in stores. Unless you squeezed it yourself juice is not as healthy as you think and is not an acceptable substitute for drinking water.
Coffee and Tea
Coffee and tea are enjoyed every day by people around the world. Tea is the number one consumed beverage in the world. Does this mean they are good for you? Coffee and tea in moderation are not harmful to you. Moderation means 1-2 six ounce cups per day. Not two venti size from the posh coffee shops. Contrary to some publicized studies, this does not count toward your 64oz of water per day. Caffeine is a diuretic, which means it causes you to lose more water through increased urine production. If your first “glass” of water in the morning is a cup of coffee you are going to further dehydrate yourself instead of rehydrate.
Naturally caffeine free herbal teas are acceptable to count as water intake and can be a good option for people who state they need water to have more flavor.
For most people alcohol can be beneficial if ingested in moderation. Alcohol has been shown to increase levels of HDL’s (good cholesterol), which can decrease the risk of coronary heart disease. Excessive consumption, however, increases the risk of certain forms of heart disease, inflammation of the pancreas, gastrointestinal tract damage, vitamin and mineral deficiencies, hepatitis, cirrhosis of the liver, a variety of cancers, hypertension, stroke, and irreversible brain damage. Moderation is defined as one drink per day for females and no more than two per day for males. Alcohol should only be consumed by people of legal drinking age, in moderation, and with meals. This is important because alcohol requires no digestion and is metabolized by the liver and other tissues. Alcohol is also a diuretic and will increase the loss of water in the body.
In good health,
Dr. Kim Bruno
- Colton, K. Smart Guide to Healing Foods, 1999.Wardlaw, G, Kessel, M. Perspectives in Nutrition, 2002.
- Willett, W. Eat, Drink, and Be Healthy, 2001.