How much water you need to drink to optimize your health and optimize performance?
Why is water important?
Water is vital to life and humans need adequate water to perform a wide variety of essential bodily functions (1). Without water intake, humans can only live a few days (2). Did you know that adults are made of about 55-60% water by weight (3,4). Up to 75% of American adults are chronically dehydrated (5). How much water we need varies based on individual variables such as age, health issues, environment, exercise patterns, diet, and other factors. Staying hydrated has significant impacts on your health so familiarize yourself with aspects of hydration to benefit your overall wellbeing.
So how much water per day do you need?
Daily water recommendations generally range from 2–2.7 L/day (up to 11.5 cups) for adult females and 2.5–3.7 L/day (up to 15.5 cups) for adult males (1,6). Many experts simply recommend eight 8 ounce glasses of water per day which comes out to be 2L of water per day (4). Therefore for adult males and females 2L should be the minimum daily water goal. The amount of water you need depends on the individual. If you live in a hot/warm climate or you spend much time outdoors where you lose water through perspiration you should drink more water. If you have a medical condition like fevers, infections, vomiting, or diarrhea you should drink more water. Also if you are very active and lose much water through perspiration then you should be drinking more water. Always consider your personal lifestyle when adjusting your water intake.
How do you know if you've drinking enough water? Do you know how to recognize dehydration?
Water is lost from the skin, lungs, gastrointestinal tract, and kidneys (6). Dehydration results when water losses from the body exceed water replacement (6). Our bodies have carefully regulated mechanisms to signal us to intake more fluids. When we need more water our body will tell us that we are thirsty (4). Using your urine color is a good indicator of hydration status (7). In general the darker your urine the more dehydrated you are and the lighter your urine the better so aim to have pale clear urine (4). Also if you feel dizzy when you stand up especially after a long work out at the gym or after a long run that could also be a sign of dehydration called orthostatic hypotension (8). If you feel dizzy regularly you should call your doctor as this may represent a more serious medical issue. Feeling hungry or getting cravings may actually be a sign that you are dehydrated (9). If you're not sure if you're eating out of hunger vs. eating out of thirst it may help to drink a glass or two of water and wait to find out if you were just thirsty or really hungry. Other symptoms of dehydration include fatigue, headaches, and dry skin (10). Also, you can drink too much water so ensure you don't go overboard and drink too much as being overhydrated can lead to a variety of health consequences as well. If your urine is completely clear after drinking too much water then you might be overhydrated so you can back off.
What are the health benefits of hydration?
There is an abundance of data showing that maintenance of a good hydration status is good for your health. Being overhydrated does not appear to benefit your health but rather staying well hydrated is key for human health. Studies show that being well hydrated:
1) maintains good brain function (11-16)
2) helps avoid constipation (2, 4, 17)
3) helps to optimize physical performance (2, 4, 18)
4) facilitates weight loss (4,19-22)
5) maintains kidney health (2, 4, 23, 24)
6) helps keep skin hydrated (4, 25)
Water rich foods
Did you know that water also comes from food? It is estimated that about 20% of our daily water from from food (2). Try to incorporate water rich foods to meet your hydrations goals. In general these include fruits and vegetable that also have a slew of other health benefits. Here are a few examples:
90-99% water content: Fat-free milk, cantaloupe, strawberries, watermelon, lettuce, cabbage, celery, spinach, pickles, squash (2, 26).
80-89% water content: Fruit juice, yogurt, apples, grapes, oranges, carrots, broccoli (cooked), pears, pineapple (2, 26).
70-79% water content: Bananas, avocados, cottage cheese, ricotta cheese, potato (baked), corn (cooked), shrimp (2, 26).
The bottom line: Tips on staying hydrated.
1. Think of drinking water as medicine rather than for pleasure. I always tell patients that getting enough water is like putting enough oil in the engine to ensure your car runs smooth.
2. Aim for a minimum of 2 liters of water per day = 8 x 8 oz. glasses
3. Get a water bottle and fill it up with 2L of water. Think of this as a medicine bottle and make sure you take your daily dose.
4. Start your day by drinking a large volume of water to get your system going. Also drinking earlier in the day rather than later in the evening will help you avoid frequent nighttime bathroom trips.
5. If you work up regularly weigh your self before and after your workout and the difference in weight is water loss. You only have to do this a few times to gauge how much you need to replenish post work outs.
6. Use indicators of hydration and listen to your body: thirst, urine color, energy levels, other symptoms.
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11. Armstrong LE, Ganio MS, Casa DJ, Lee EC, McDermott BP, Klau JF, Jimenez L, Le Bellego L, Chevillotte E, Lieberman HR. Mild dehydration affects mood in healthy young women. J Nutr. 2012 Feb;142(2):382-8.
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17. Arnaud MJ. Mild dehydration: a risk factor of constipation? Eur J Clin Nutr. 2003;57:S88–S95.
18. Goulet, Eric D.B., Mélançon, Michel O., Lafrenière, David, Paquin, Jasmine, Maltais, Mathieu, Morais, José A. Impact of Mild Hypohydration on Muscle Endurance, Power, and Strength in Healthy, Active Older Men, Journal of Strength and Conditioning Research: December 2018 - Volume 32 - Issue 12 - p 3405-3415.
19. Thornton SN. Increased Hydration Can Be Associated with Weight Loss. Front Nutr. 2016;3:18. Published 2016 Jun 10.
20. Jeong JN. Effect of Pre-meal Water Consumption on Energy Intake and Satiety in Non-obese Young Adults. Clin Nutr Res. 2018;7(4):291-296.
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26. Altman P. Blood and Other Body Fluids. Washington DC: Federation of American Societies for Experimental Biology; 1961.
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