(HW) June 2014
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MIT: Department of Athletics, Physical Education and Recreation
Hydration @ MIT
Why is hydration so important?
Nearly 60% of our body’s weight is made-up of water, so it is no
surprise that hydration is essential to life. Water is crucial to almost
every body function, including body temperature regulation,
nutrient metabolism, organ function, waste elimination, physical
performance, and cognitive functioning.
Since water is so central to the human body, the consequences of
having too little can range from uncomfortable to devastating
symptoms. The state of using and/or losing more water than you
take in is called dehydration.
You can become dehydrated for many reasons such as excessive
respiration (talking a lot or breathing quickly), sweating (during
sport or a humid day), vomiting or diarrhea, and alcohol
consumption. It is important to remember that you may need to
drink more when experiencing these circumstances.
Some signs and symptoms of dehydration are listed below.
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Headache
Dizziness
Fatigue
Thirst
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Dry or sticky mouth
Darker yellow urine
Dry, cool skin
Muscle cramps
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Fast heartbeat
Fast breathing
Irritability or confusion
Dehydration Influences Athletic and Academic Performance
Dehydration impairs your ability to function at optimum mental and physical capacity. Even mild to moderate
levels of dehydration—a loss of 1.5-2% of body mass—will negatively impact your performance in these areas.
Cognitive effects of mild dehydration include decreased reaction time, lessened short- and long-term memory
capabilities, shortened attention span, poorer arithmetic ability, and weaker perceived discrimination. In
addition, you will experience enhanced fatigue and moodiness. In sport, moderate dehydration decreases overall
performance, including consequences like reduced endurance and strength. Researchers have shown as much as
a 45% reduction in high-intensity exercise capacity with a 2.5% loss of body weight from dehydration.
To prevent these ramifications of dehydration you need to remember to drink hydrating fluids even when you
do not feel thirsty. Our natural thirst response does not initiate until we are already 1-2% dehydrated, so to
prevent the possibility of even slight intellectual and physical decline, drink up!
Natural Response to Dehydration
Dehydration can be serious; our bodies have innate physiological mechanisms to correct dehydration. Our
kidneys—the chief organ in charge of fluid status—senses dehydration mainly through plasma sodium levels
and, to a lesser extent, through blood volume. When sodium is too low, a state called hyponatremia, our brains
secrete Antidiuretic hormone and stimulate an increased thirst response. These events collectively cause our
kidneys to retain water and make us thirsty to consequently drink more fluid. Both these mechanisms safeguard
the body from becoming severely dehydrated.
(HW) June 2014
2
MIT: Department of Athletics, Physical Education and Recreation
How much liquid should I be drinking?
According to the recommendations made by the Institute of Medicine (IOM), men should be drinking 13 cups
(~3 liters) and women, 9 cups (~2.2 liters) of beverages per day. These IOM recommendations are not
individualized, but they are a good place to start. On certain days or at certain times, like on a very humid or
cold day, or when you have sweat a lot, you will need to drink more fluids than the IOM suggests to achieve
adequate hydration.
An alternative, and perhaps easier way to conceptualize how much fluid you need to drink each day is to use the
following formula: Drink ½ of your body weight in ounces.
Bodyweight (lbs.) x 0.50 = # of ounces you should drink per day
(Example: 140lbs x 0.50 = 70lbs. This 140lb individual should drink 70 ounces per day to stay hydrated)
Caution: While adequate hydration is crucial to health, it is possible to over-hydrate. Over-hydration occurs when the
body takes in or retains more water than it excretes, leading to electrolyte
imbalances (i.e. sodium levels are diluted), which prevent body cells
Check Nutrition Labels and
from functioning properly. Over-hydration is most common in
Choose a Healthy Drink
individuals with kidney malfunction, however you should still be careful
not to overdo it even if your kidneys are healthy. Always keep your
 Pick Unsweetened, Low-Sugar options
personalized recommendation in mind.
Tips for staying hydrated at MIT
1. Utilize reusable water bottles – Having one with you every day
ensures access to water wherever you are and FREE refills.
2. Drink a glass of water at every meal – This will get you in the
habit of drinking even when you’re not feeling thirsty, which
will ultimately prevent dehydration.
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Avoid drinks with fat such as Starbucks®
Frappuccino® bottle coffee drinks. Aim
for <2.5g Total Fat and 0g Saturated Fat.
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Be cautious of diet drinks. (These often
contain high amounts of artificial
sweeteners that can cause stomach aches
in some people.)
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Choose drinks with little to no calories. In
general, we consume enough calories
through food and do not need more from
our drinks.
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Check serving size if the beverage
contains any calories, sugar, or fat to make
sure you don’t consume a lot of these
components.
3. Add natural flavoring - Lemon or other fruit slices, and herbs,
like basil and mint, can add a refreshing boost to your drink!
4. Eat food with high water content - Examples of fruits with a lot
of water are watermelon, cantaloupe, grapefruit, peaches, and
strawberries. High water content vegetables include broccoli,
cabbage, cucumber, zucchini, celery, tomatoes, and peppers.
5. Track the amount of fluids you drink each day - Write down
when, what, and how much you drink in a day, to make sure
you are drinking the recommended 13 cups (men) or 9 cups
(females) of beverages per day.
Healthy drinks at LaVerde’s
1. Seltzer and other Carbonated Waters with
no sugar: Schweppes©, Polar®, and Poland
Spring® Sparkling
2. Vitaminwater® Zero (sweetened with
Stevia)
3. Pure Leaf Tea™ Unsweetened
4. Non-fat and Low-fat Milk
Resources: The Natural Hydration Council. 2014. Retrieved from,
http://www.naturalhydrationcouncil.org.uk/hydration-facts/fact-sheets/
Popkin BM, D’Anci KE, & Rosenberg IH. Water, Hydration and Health. Nutrition
Reviews. 2010; 68(8): 439-458.
MedlinePlus. Dehydration. National Institutes of Medicine. 2014. Retrieved from,
http://www.nlm.nih.gov/medlineplus/ency/article/000982.htm.
Bastin, Sandra. Water Content of Fruits and Vegetables. University of Kentucky, College of Agriculture. 1997.
Jeukendrup, A. & Gleeson, M. Dehydration and its effects on performance. Sport Nutrition. Human Kinetics. 2010. Retrieved from,
http://www.humankinetics.com/excerpts/excerpts/dehydration-and-its-effects-on-performance