Hydration is extremely important when it comes to performance. Being even slightly dehydrated can decrease energy levels as well as leave you more prone to injury and disease. But how much water do you actually need to drink? Let’s dive in.
The common wisdom regarding water intake is that you should drink eight 8-oz glasses of water each day in order to remain well hydrated. This comes out to about 2 L total.
While this is a generally good rule of thumb for sedentary adults, like most topics regarding human health and performance, there is a large amount of individual variability.
Differences in size, where you live, physical activity, and the foods you eat all have a huge effect on how much water you should be drinking during the day. (Karpinski & Rosenbloom, 2017)
A small person, say 5’2” who is generally sedentary and spending most of their day indoors may only need to take in 1.5 L of fluids each day in order to remain euhydrated (normal hydration levels).
But a larger person, say 6’4” who is very active and running sprints outside in the heat of summer may need to take in 5-6 L of water just to keep themselves from becoming dehydrated.
According to the Sports Nutrition Handbook the dietary recommendation for water are set at 3.7 L/d (Liters per day) for men, and at 2.7 L/d for women. (Karpinski & Rosenbloom, 2017)
Now for many of you this may sound like an impossible amount of water to drink in a day. If eight 8-oz cups only equals ~2 L, and most people fail to even reach that.
BUT
This fluid recommendation includes fluid from all sources, meaning it includes the water you get from the foods you eat. They go on to state that about 80% of your water needs are provided by the fluids you ingest, and the remaining 20% comes from the foods you eat. (Karpinski & Rosenbloom, 2017)
Still though, for men the recommendation is set at 3.7 L/day which if you take 80% of that you still need to drink ~3 L of water each day in order to remain well hydrated. And for women 80% of their recommended daily intake of 2.7 L equals ~2.2 L.
The easiest way that I have found to stay consistently hydrated is to always have multiple large stainless steel water bottles filled with water with or without a small electrolyte tablet to add a little flavor and increase fluid absorption.
Each day I fill up my 1 L water bottles (I bring 2 of them each day), and bring them with me to work. That way I know that I am at least getting 2 L before leaving work.
After work, my exercise schedule will dictate how much more I drink. If I am going to go out and run sprints in the heat then I will refill one of my water bottles and add some more electrolytes to it. If I am going to stay in for the night I will allow my thirst to regulate how much I drink the rest of the night. Generally, I will take in multiple 8 oz glasses of water on my own.
Now I became really obsessive about hydration when I was in PA school. For about 6 months I was taking a medication called Accutane which is for skin issues. This medication is very powerful and can lead to liver issues if incorrectly administered. One of the important factors is that you need to remain well hydrated so that your body can adequately process the medication. Since this time I have kept up the hydration habit.
So I hope that this has been helpful.
In summary, men need to be drinking about 3L of water each day and women need to be drinking about 2L.
This will vary depending on if you are exercising outdoors, vs sitting in the AC all day.
Next week we will be discussing more advanced hydration strategies including electrolyte tablets, filtered water, and how to hydrate around exercise.
Again this is Floyd Meyer reminding you to Drink Better so you can Do More!
References
Karpinski, C., & Rosenbloom, C. (2017). Sports nutrition: a handbook for professionals. Chicago: Academy of Nutrition and Dietetics.
Popkin, B. M., D’Anci, K. E., & Rosenberg, I. H. (2010, August). Water, hydration, and health. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/20646222.
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