Water, Alcohol, & Caffeine
Do Your Drinking Habits Support Health?
Over the years, there have been many health recommendations and warnings about drinking water, alcohol, and caffeine. Some of the things you may have heard are not based on science, but are actually myths.
Read on to learn…
  • Do you really have to drink 8 cups of water a day to avoid dehydration?
  • Can “moderate” alcohol intake be healthy? And, if so, what is considered “moderate?”
  • Does caffeine really “rob” your body of water? And, how much coffee is safe to drink?
  • How many calories are hiding in your favorite alcohol and coffee drinks?
Water is the body’s most indispensable nutrient. In fact, you can survive for weeks without food, but you can live only a few days without water. Water makes up between 50 and 75% of your body’s weight. Leaner people have proportionately more water because muscle tissue is nearly 75% water by weight while fat tissue is only about 10% water by weight. 

Why is water so important?
Water serves numerous functions in the body. For example, it carries nutrients throughout the body, cleans the body of waste products, participates in many chemical reactions in the body, helps maintain the body’s temperature, and serves as a lubricant and shock absorber inside the eyes, spinal cord, joints, and amniotic sac surrounding a fetus. Clearly, water is essential to health.

How much water do you REALLY need?
In February 2004, the National Academy of Sciences, Institute of Medicine issued new recommendations for water. The report basically said that the vast majority of healthy people can adequately meet their daily hydration needs by simply drinking when they are thirsty. This may seem like common sense, but over the years several people have challenged this idea by claiming that we are all walking around slightly dehydrated. Apparently, this is not true!

While the report did not specify exact requirements for water, it did set the following general recommendations for women and men:
  • Women need an average of approximately 2.7 liters (91 ounces or ~11 ½ cups) of total water per day.
  • Men need an average of approximately 3.7 liters (125 ounces or ~15 ½ cups) of total water per day.
NOTE: This includes water from ALL beverages and foods, not just pure drinking water. In fact, about 80 percent of people's total water intake comes from drinking water and other beverages – including caffeinated beverages—and the other 20 percent is derived from food. 

Is thirst always a good indicator of your hydration needs? 
For some people, thirst may not always be a good indicator of hydration needs. Water needs increase in hot climates and with heavy physical activity. So, athletes who train several hours a day in the heat should NOT rely on their thirst, but should instead stick to a strict drinking schedule. Dehydration of as little as 1-2% of one’s body weight has been shown to impair muscle endurance. At 3-4% dehydration, muscle strength and endurance significantly drop and performance is impaired. Click here for more info on what and how much to drink before, during, and after intense exercise.

In addition to athletes, children and the elderly may not be able to rely solely on thirst to guide their drinking habits. These populations have a less acute sense of thirst and may have reduced kidney function. In addition, many older adults take diuretic medications, which significantly increase fluid loss and thus increase fluid needs. 

Do I have to drink plain water, or do other beverages count?
Contrary to what a lot of people have said over the years, plain drinking water is not needed as long as enough water is obtained from various foods and beverages. 

What about caffeine and alcohol?
Despite claims that caffeine dehydrates you, caffeinated beverages (as well as alcoholic beverages) CAN actually contribute to your daily water needs. While it’s true that caffeine is a diuretic, its effects are temporary and do not significantly increase your 24-hour urine output. So, consuming caffeine doesn’t increase your risk of heat injury. In fact, there appears to be an adaptation response in habitual consumers of coffee, tea, and other caffeinated beverages. In other words, the more regularly you drink it, the more your body is able to hold onto the water it provides. So, the popular notion that for every cup of coffee you consume you need to drink a cup of water to replace lost fluid is false.

But WAIT, that doesn’t mean you shouldn’t try to drink more plain water!
While you don’t have to rely on plain water to meet your hydration needs, it’s still a good idea to make plain water your beverage of choice. Sodas, fruit drinks, and many gourmet coffee and tea drinks have a lot of added sugar (which contributes a lot of “empty calories!”). Even 100% fruit juice, though loaded with disease-fighting nutrients, is high in calories and doesn’t fill you up the way that eating a whole piece of fruit would. Diet sodas and other artificially sweetened beverages are a calorie-free option, but they should be enjoyed only in moderation. Click here for more info about the safety of sugar substitutes in diet drinks. 

Bottom Line
  • Most of the time, make plain water your beverage of choice. Carry a water bottle with you to school and/or work so that you can drink when you feel thirsty.
  • To avoid unwanted weight gain…
    • Limit juice to no more than one 8 oz. cup a day (and make sure it’s 100% fruit juice). Instead of fruit juice, enjoy more whole pieces of fruit (since they are less concentrated in calories and much more filling).
    • Try “diet” versions of your favorite sodas. But, be sensible, and don’t overdue it with artificial sweeteners. One to two cans of diet soda a day is sensible; one to two liters a day is NOT!
    • Enjoy high calorie gourmet coffee/tea drinks and alcoholic beverages as “special treats.” If you choose to drink one of these “special treats” a day, make sure it’s IN PLACE OF other “empty calorie” treats.
    • At coffee shops, ask for fat free milk (instead of whole milk), and skip the whip cream. You’ll save 100-200 calories.\
  • Be sensible with alcohol and caffeine. Both are safe in moderation. But, make sure you read on to learn what exactly is considered “moderate.”
Click on the link above to learn…
  • How much alcohol is considered “moderate?”
  • How many calories are hiding in your favorite drinks?
Click on the link above to learn…
  • The pros and cons of consuming caffeine.
  • The amount of caffeine that is considered safe.
  • The caffeine content of your favorite drinks.
Sheri Barke, MPH, RD
COC, Student Health & Wellness Center
Rev. 2005