The Spill On Hydration Habits

Carla Nowicki, MS, RD, CSSD, CSCS

It is no secret that water is the fountain of youth and health. It keeps you… well, alive. Without water, the average person only lasts about three days. Yet majority of adults and athletes walk around dehydrated daily. It is estimated that 75% of adults don’t get the Institute of Medicine (IOM)’s low recommendations for hydration of ten - eight ounce glasses of water a day (1). Most of them don’t even know they are dehydrated.

Water and Your Health

Water is used for practically every cell in your body, making up about two thirds of you. Without proper water intake, you are not efficiently running on all cylinders. This is why proper hydration is usually one of the first and most common recommendations I give. Progress in almost any and every goal you have is affected by hydration. Even though dehydration is difficult to state as direct cause of disease, the stress it puts on your body sets up for endless poor health outcomes (2).

For starters, your blood is kept moving by your heart. Water circulates the body in your blood stream. As you become dehydrated your blood thickens, creating extra stress on your heart throughout the day. This same dehydration decreases the ability for your brain to think clearly. Recent studies have found that even a 1.36% loss of body weight causes increased perception of task difficulty, fatigue, headaches, and loss of concentration (3).  

Best of all, weight loss and body composition changes are seen more effectively and quicker with proper hydration and water intake. Who doesn’t want a better body fat percentage? Drinking just 2 liters of water increases metabolism by about 200 kcals a day more than those drinking ½ a liter a day4.  Even better, good water intake means a better workout to crush those body composition goals.

Exercise and Dehydration

The easiest way for you not to perform to your potential is to become dehydrated. Whether or not you are looking to be a competitive athlete, you exercise for a purpose. You aim to get the most out of every workout you have. There isn’t any reason to waste time and effort by just feeling and performing like crap. Depending on what you are doing, even a 1% decrease in body weight from dehydration can cause performance decline (3,5). In the eyes of performance this is what you are putting on the line as dehydration progresses:

1% Dehydration- increased fatigue, decreased reaction time, decreased fine motor skills, decreased memory, decreased visual concentration (5)

2% Dehydration- Decreased skill, strength, endurance, and speed (6,7)

4% Dehydration- Dizziness, nausea (8)

>6% Dehydration- Risk of Heat Stroke- hallucinations, coma, death (9)

Fluid loss is inevitable while working out. One of the most powerful purposes for water in your body is the regulation of body temperature. Sweat happens, and should happen. Without sweat and proper blood circulation, your core body temperature would soar past healthy living conditions and creating temporary and possibly long-term effects on the body and brain. The goal for hydration with exercising is to keep within 2% of your body weight to ward of risk of injury and keep workouts productive.

Injury risks

When you are injured, you are just plain out. You are limited by the number of exercises you can do, forced to decrease your intensity and take extra time off. Overall it just gets frustrating. Injury risks are exponentially greater when dehydrated. This is a double fold effect of how your body and mind react to dehydration. As mentioned before, when you are even the slightest bit dehydrated, thinking quickly and clearly becomes challenging (3). When your exercise and play sports, you are asking your body to react carefully to responses around you at a rapid pace. Even without contact injuries, lack of proper concentration can make you step the loose technique and form. The second part is the actual muscle fibers themselves. Think of your muscles like a sponge. A wet sponge stretches and twists with its needs. That same sponge, when dry, one little twist and it easily tears. Soft tissue injuries like muscle tears are far more common when dehydrated.

Thirst, Common Recommendations and Their Problems

Thirst isn’t the best way to judge your hydration status. For you to notice you are thirsty, your body is already 1-2% dehydrated (10). Thirst is your body’s way of telling you there is a problem, not a preventative trigger. As you age, the thirst response is delayed even further (11). Keeping yourself with a hydration schedule is a far better way to set up your day for success. There is also no such thing as training your body to be more adapt to being dehydrated. Your body will not perform better when you are running low on water just because you are used to it.

Front loading your hydration is helpful for a few reasons. First, you wake up dehydrated. You need to replace what you lost over the night. A morning glass of cold water helps you wake up and get your metabolism working in the right direction. That same glass of water gives you a head start on your daily intake. The more you space out the water you take in, the more beneficial it is. Start early and often getting your water in throughout the day. Always carry a waterbottle with you to make this easy. You should be thinking when you leave- phone, wallet, keys, waterbottle. An easy tracking method to know how much you have had, add rubber bands on the bottom of your waterbottle to count how many you have had today. Lastly, no one likes to get up a bunch of times in the middle of the night to pee. Improve your sleep habits and drink more earlier on to avoid the midnight bathroom breaks. If you need a little boost for flavor, try adding a couple pieces of fruit or fresh herbs. One major problem of the IOM recommendations for hydration is that it doesn’t take into account what makes needs different from person to person. Not everyone is the same size. Bigger people need more water. Children and elderly lose water more rapidly and need more water per size and need to drink more, and more frequently. Heavy sweaters sweat more during exercise and need to replace it. Those who live in hotter climates need to drink more throughout the day.

Water is heavy, weighing in about 1 pound per 20 fluid ounces. People are told to weigh themselves in the morning since it is the most consistent weight. This also means you are consistently will be slightly dehydrated when you wake up. On a slightly gross thought, you sweat on average 2-3 pounds a night. Depending on your size, that is already starting you off at a 1-2% dehydration for the day.

Your Hydration Needs

Think of your individual needs as a math equation with some trial and error. Start with taking your body weight, multiplied by 0.5 for adults, and 0.6 for children and elderly. Then, add in your individualized needs for exercise. This is the part that you will need to test out. Start by drinking 20 fluid ounces for every hour you workout, 25-30 fluid ounces if you are in the heat of summer. If you are a heavy sweater, add 5-10 fluid ounces more an hour. You can test this by weighing in and out of a workout. Your goal is to maintain within 2% of your starting weight. Just make sure you don’t become over-hydrated and gain water weight above where you started.

Drinking too much water can be just as dangerous as dehydration. Thankfully your body is pretty great at voiding excess fluids. Over hydrating dilutes the electrolyte balance of your blood. Adding salt into your water can help you avoid the dilution. When you sweat out it is a combination of electrolytes and water. It’s important to consider both. There are a couple ways you can tell if you are properly hydrated-

  1. Your pee should be light yellow to almost clear. Even if you take a multivitamin, proper hydration shouldn’t let it be bright or dark yellow. If your pee is the color of apple juice or darker don’t workout. The risk isn’t worth it that day.

  2. You should be going to the bathroom eight to ten times a day. If you are only going five to six, you need to drink more. When you first increase your hydration levels, expect yourself to go a lot more frequently until your body gets used to it.

  3. Weight yourself in and out of workouts. Quick weight loss is primarily fluids. If you notice you are weighing in light before training, you may be pretty dehydrated.

When To Have A Little More

There are some important times to remember to drink more than usual. Alcohol is a potent diuretic. When out drinking, it is a good rule of thumb to drink one eight-ounce glass of water for every drink you have before you go to bed, or at a minimum by the next morning. This helps the hangover and lowers the risk of injury. Most people think that coffee is a diuretic as well. Thankfully for the morning bean addicts, it isn’t as bad as what you may think. Caffeine at normal levels (less than 240mg) do not count as a diuretic (12). A normal cup of coffee has about 60-150mg of caffeine. Caffeinated teas come in even lower at about 40-60mg.  

Take change slow at first. Your body will take some extra time to get used to being hydrated. You will find yourself looking for a place to go WAY more often while it figures out that you are going to help it, not hurt it. Add 10-20 fluid ounces daily from where you are at until you reach your hydration needs.

You can live in a chronic state of dehydration and get by, or you can take some small steps to put your body in its optimal state. Consistent hydration can unlock doors and potential you only hope for. Hydration improves your brain function, decreases stress, improves performance, and reduces injury risk. With all that plain-old free water can do for you, Its time you grab your bottle and fill it up.


  1. Survey of 3003 Americans, Nutrition Information Center, New York Hospital-Cornell Medical Center (April 14, 1998).

  2. Armstrong, L. E. (2012). Challenges of linking chronic dehydration and fluid consumption to health outcomes. Nutrition Reviews.

  3. Armstrong, L. E., Ganio, M. S., Casa, D. J., Lee, E. C., McDermott, B. P., Klau, J. F., … Lieberman, H. R. (2012). Mild Dehydration Affects Mood in Healthy Young Women. Journal of Nutrition, 142(2), 382–388.

  4. Buschmann, M., Steiniger, J., Hille, U., Tank, J., Adams, F., Sharma, A. M., … Jordan, J. (2003). Water-Induced Thermogenesis. Journal of Clinical Endocrinology and Metabolism, 88(12), 6015–6019.

  5. Ganio, M. S., Armstrong, L. E., Casa, D. J., McDermott, B. P., Lee, E. C., Yamamoto, L. M., … Lieberman, H. R. (2011). Mild dehydration impairs cognitive performance and mood of men. British Journal of Nutrition, 106(10), 1535–1543.

  6. Baker, L. B., Dougherty, K. A., Chow, M., & Kenney, W. L. (2007). Progressive dehydration causes a progressive decline in basketball skill performance. Medicine and Science in Sports and Exercise, 39(7), 1114–1123.

  7. Cheuvront, S. N., Carter, R., & Sawka, M. N. (2003). Fluid balance and endurance exercise performance. Current Sports Medicine Reports, 2(4), 202–208.

  8. Van Nieuwenhoven M, Vriens B, Brummer R, Brouns F. (2000). Effect of dehydration on gastrointestinal function at rest and during exercise in humans. European Journal of Applied Physiology, vol. 83, issue 6 (2000) pp. 578-584.

  9. Coris E.E., Ramirez A.M., Van Durme D.J (2004). Heat illness in athletes: the dangerous combination of heat, humidity and exercise. Sports Med. 34(1):9-16.

  10. Sawka, M. N., & Montain, S. J. (2000). Fluid and electrolyte supplementation for exercise heat stress 1 – 4, 72, 564–572.

  11. Phillips, P. A., Bretherton, M., Risvanis, J., Casley, D., Johnston, C., & Gray, L. (1993). Effects of drinking on thirst and vasopressin in dehydrated elderly men, 264(5):R877-R881.

  12. Armstrong, L. E., Casa, D. J., Maresh, C. M., & Ganio, M. S. (2007). Caffeine, Fluid-Electrolyte Balance, Temperature Regulation, and Exercise-Heat Tolerance, Exerc Sport Sci Rev. Jul;35(3):135–140.