Updated: Oct 23
Let's talk about water. We all know that we need water every day to survive, but how much do we actually need? The research on this is conflicting and depends on a lot of factors like how much you exercise, what the climate is where you live, what medications you take, overall health status, and your age. Due to this, there isn't one singular answer, but we're gonna dive into all the variabilities so that you can make the best decision on your water intake. Our bodies are around 60% water- this is why we need it to survive! Water helps regulate your body temperature, normalizes blood pressure, maintains electrolyte balance, lubricates joints, protects tissues, and helps to get rid of wastes via urination and sweating. (1,2) One general rule says 8 cups per day for the average person. (2) Other recommendations say as much as 12-15 cups per day. (3)
Exercise is the first factor that changes water intake needs. When we sweat we lose water as well as electrolytes that help us stay hydrated. More water needs to be drunk before, during, and after a workout to make up for this. You need 7-10 oz of water for every 10-20 minutes of exercise and then 16 oz of water after a workout for every pound lost. (4) This is because most of the weight we lose during a workout is water weight in the form of sweat. The next factor is the environment. It’s well known that we need more water when it's hot and humid out, but did you know that dehydration occurs more often in cold weather? In hot weather we are sweating more, leaving us dehydrated. But in cold weather, we need to breathe heavier and it takes our body more energy to warm the cold air we take in, leading to more fluid being used. (5) We also aren't thinking about drinking water in cold weather like we are in hot weather.
Medications and health status are the next hydration factor. When we are sick with a fever, have diarrhea, or are vomiting we are expelling much more water than when we aren't sick. Some medications can cause dehydration because they have a diuretic effect, meaning they make you urinate more often than usual. Common diuretic meds include blood pressure and heart meds and some kidney disease medications. (6). Our age also greatly affects our hydration status. As we get older we actually lose the receptors that tell our brain we are thirsty and need water. This causes us to drink less often and not be aware when we are dehydrated or thirsty.
So it's important to continue to drink water throughout the day regardless if you feel you are thirsty. Staying hydrated can also come from other sources besides water. Fruits and vegetables can also contain a lot of water, especially celery, cucumbers, watermelon, and spinach. Milk, juice, sports drinks, and teas are also mostly water. Now that we know what affects our hydration status let's figure out how much water we actually need in a day. It’s important to be aware of when we get dehydrated. If you rarely feel thirsty, or your urine is light yellow to colorless then you are probably hydrated! If you have a headache, have dark urine, or feel extra thirsty then you are definitely dehydrated and need to find some water. You should drink a glass of water with each meal, before, during and after exercise, and when you feel thirsty. Taking all of this into consideration, the best recommendation is to drink ½ oz - 1 oz of water for each pound you weight, every day. This means that if you weigh 150 lbs you should be drinking 75-150 oz of water a day. That is around 9-15 eight oz glasses every day for that person. Once you figure out how much water you should be drinking it may seem like a lot, but once you start drinking the correct amount you will have more energy, snack less often and your body will get used to the amount!
Dietary reference intakes for electrolytes and water. U.S. National Academies of Science, Engineering, and Medicine. https://www.nationalacademies.org/our-work/dietary-reference-intakes-for-electrolytes-and-water. Accessed Oct. 2, 2020.