The human body, which is made up of between 55 and 75 percent water (lean people have more water in their bodies because muscle holds more water than fat), is in need of constant water replenishment.
Your lungs expel between two and four cups of water each day through normal breathing – even more on a cold day. If your feet sweat, there goes another cup of water. If you make half a dozen trips to the bathroom during the day, that’s six cups of water. If you perspire, you expel about two cups of water (which doesn’t include exercise-induced perspiration).
A person would have to lose 10 percent of her body weight in fluids to be considered dehydrated, but as little as two percent can affect athletic performance, cause tiredness and dull critical thinking abilities. Adequate water consumption can help lessen the chance of kidney stones, keep joints lubricated, prevent and lessen the severity of colds and flu and help prevent constipation.
So how much water do you need?
This isn’t an easy question to answer. A healthy adult’s daily fluid intake can vary widely. Most people drink fluid to quench thirst, to supply perceived water needs and “out of habit.” At least three approaches estimate total fluid (water) needs for healthy, sedentary adults living in a temperate climate.
- Replacement approach. The average urine output for adults is 1.5 liters a day. You lose close to an additional liter of water a day through breathing, sweating and bowel movements. Food usually accounts for 20 percent of your fluid intake, so you if you consume 2 liters of water or other beverages a day (a little more than 8 cups), along with your normal diet, you can replace the lost fluids.
- Eight 8-ounce glasses of water a day. Another approach to water intake is the “8 x 8 rule” – drink eight 8-ounce glasses of water a day (about 1.9 liters). The rule could also be stated, “drink eight 8-ounce glasses of fluid a day,” as all fluids count toward the daily total. Though this approach isn’t supported by scientific evidence, many people use this basic rule as a guideline for how much water and other fluids to drink.
- Dietary recommendations. The Institute of Medicine recommends that men consume 3 liters (about 13 cups) of total beverages a day and women consume 2.2 liters (about 9 cups) of total beverages a day. These guidelines are based on national food surveys that assessed people’s average fluid intakes.
Beyond the tap: Many sources of water
You don’t need to sip from your water bottle all day to satisfy your fluid needs. Your diet, including the beverages you drink, can provide a large portion of what you need. In an average adult diet, food provides about 20 percent of total water intake. The remaining 80 percent comes from beverages of all kinds. Keep in mind that beverages that contain caffeine and carbonation actually dehydrate you as opposed to hydrating your body. If you drink a large amount of these types of drinks, you should consume that much more good fluid.
If you’re sick of the blandness of water, try adding calorie flavor with a calorie-free powder mix like Crystal Light. I always have a gallon of it in my refrigerator, ready to drink. And the amount of water that I drink every day, I go through it pretty quickly.
Fruits and vegetables – besides being good sources of vitamins, minerals and fiber – contain lots of water. For example, oranges are 87 percent water, and cucumbers are 95 percent water. Milk, juice and other beverages also have large amounts of water. Conversely, dried fruits, nuts, grain products and baked goods generally contain less water.
Staying appropriately hydrated will increase sports performance, help to clean out the body, improve the tone of your skin, increase your alert level, and many other benefits. Drinking adequate amounts of water is just as important on your quest to get your hot bod as diet and exercise!