Water, so simple (drink it!). Yet, so complex (how much?!). We’re gonna hit you with the down and dirty.
What’s the purpose of water in the body?
Water is involved in EVERY process in the body. It’s used as a transport medium; the majority of your blood is water. Think of that for a second: water helps transport OXYGEN and NUTRIENTS. That’s what red blood cells do; they carry oxygen rich blood to working tissues in addition to other nutrients. Low hydration = diminished capacity to carry oxygen and nutrients. That affects your cognition and brainpower just as much as it affects your physical ability.
Water is a lubricant. Not only does being well-hydrated help with joint pain (the discs between your spine and joints are composed of primarily water), but it also helps with digestion.
Water is a coolant, but most people know that already.
Take home point. The purpose of water is to keep us alive and allow us to thrive. This is done via the transportation of oxygen and nutrients, the cooling of the body, aiding in digesting foods and keeping our joints happy and healthy.
Dehydration: How does the body use water as a coolant, and what happens when we are dehydrated?
As water is lost from the body via sweat (cooling us down), blood pressure goes down, blood volume decreases resulting in a drop in stroke volume (volume of blood your heart pumps out per beat), and cardiac output decreases (how much total blood your heart pumps out per unit of time, generally a minute). For cardiac output think volume and force. When volume goes down, force goes up to make up for a loss of volume. Dehydration leads to an INCREASE IN HEART RATE, which is not good,.For all intents and purposes, a heart that beats faster isn’t ideal.
To make matters worse, as you get dehydrated, you actually end up sweating LESS. Well, there is a tipping point. That’s a sure fire sign of a heat-related illness. Sweating is a safety mechanism, except when sweating would kill you in the case of having LOW amounts of water. The body stops sweating in the case of heat-related injuries because you’re taking vital water away from organs, and it’s way more important to keep that heart pumping rather then cooling yourself off).
All of this leads to decline in mental and physical performance.
Take home point: Dehydration = higher heart rate, lower blood pressure, and less oxygen is delivered to brain/muscles resulting in decreased mental and physical performance.
How is water stored in the body? Bloating 101.
Water is stored in fluid within the cells (intracellular fluid [ICF]) and/or fluid outside the cells (extracellular fluid [ECF]). ICF is about 65% of total water; ECF (blood plasma, lymph fluid, etc.) is about 35%. Chloride, potassium, and sodium are three molecules that help maintain the balance between ICF and ECF. If one of those three becomes too concentrated in either ECF or ICF, the body produces hormones that help to bring the balance back. For instance, too much sodium in the ECF (think of ECF as a transport channel) will cause water to be pulled out of the ICF to bring the ratio of water to solvents in the ECF back to balance.
Pizza makes you thirsty, and it causes you to bloat up. That’s because the sodium from the pizza accumulates in the ECF, which then causes the brain to pull water from the ICF to signal thirst. You will then feel thirsty until the balance between ECF and ICF is restored.
What happens if you OVER drink? That means you have a greater amount of ICF now. That’s where the kidneys come in to bring the balance of ICF to ECF back.
Take home point: The body wants the balance of water to be tightly controlled. Any change to that balance will result in the body attempting to bring it back to balance via either consuming more water or eliminating water.
How much water should you drink on a daily basis?
Generally it’s quoted to drink a gallon of water. However, I have also heard drink 8, 8 oz. glasses per day, which would give you about half a gallon of water. That’s a pretty big swing! What does the research say? The Institute of Medicine (IOM) established an adequate intake (AI) for total water to prevent the harmful acute effects of dehydration. Every day we lose about a liter from breathing, sweating, and bowel movements, which is about 33 ounces of water. Then we add in the average water lost through urine in a day, that’s 1.5 liters, or around 50 ounces of water per day. So, we know that we need to AT LEAST consume roughly 80 ounces of water daily to make up for the average loss.
The IOM AI for sedentary men and women (19-50 y/o) is 3.7 liters and 2.7 liters per day. However, we get about 20% of our total water from foods, so that means the actual intake is 3.0 liters for men and 2.2 liters for women., or about 100 ounces for men and 80 ounces for women. Obviously, if you’re excreting more water through urine, bowel, breathing or sweating, you need to consume more water.
Take home point. Total intake should be at least 80 ounces for females and 100 ounces for males. This is based on a sedentary person.
How do you know how much water to drink before, during, and after exercise?
This is actually way easier to figure out then you think. Weight yourself before you work out to figure out how much you should drink post work out, and make sure you do this naked. Weight yourself again (naked) after your work out. How much water did you loose? You should be drinking about 1.5 liters per kilogram or 50 ounces per 2.2 pounds, which comes out to about 22 ounces per pound.
Take home point. For every pound lost during exercise, drink 20 ounces of water.
What about before exercise? That depends on what time of the day you work out. If it’s reasonable, consume ALL of the water for your day before you work out. This would be a good rule of thumb for an evening work out session. If it’s mid-day, shoot for 3/4 of your 100 or 80 ounces of water. First thing in the morning then go for at least 30-40 ounces. The research is fairly clear on this, but, rather then bore you with the research, let’s just stick to what you will actually pay attention to and do. General rule of thumb: drink 16 ounces of water per hour for females and 20 ounces of water per hour for males. More is probably better, less is certainly worse.
Can you drink too much water?
Yes, but, it’s akin to over dosing on vitamins and minerals. In over 20 years of being involved in the fitness field, I have NEVER come across anyone who has been injured or otherwise debilitated through drinking too much water. In fact, it’s almost silly to talk about it. The body has a lot of checks and balances for it’s various tasks. You would be peeing every hour if you were drinking TOO much water. So, while the easy answer is yes, the hard answer is, it’s incredibly unlikely.
Where do sports drinks and “enhanced water” fit into this?
Sports drinks, made famous by Gatorade are now sold everywhere and, are more of a bane then a boon. (Did you know the initial formulation of Gatorade has HALF THE SUGAR as it does now? They added more sugar to make it more palatable.) In my opinion, sports drinks do more harm then good. The goal of sports drinks is to replenish water lost through competing/practice, replenish electrolytes and start the recovery process earlier. It’s important to replenish electrolytes as we are just one big battery. Our system works because of electrolytes suspended in water to allow the conduction of electric current.
Generally speaking, you should consume a sports drink if you lost A LOT of water through sweating in a short period of time (playing a 90 minute soccer match in 90% humidity and 90 degrees would work). If your clothes are DRENCHED in sweat after an hour of working out, or if you’re going to be losing a lot of water via sweat through out the day (like construction workers and outside laborers) on an hourly basis then consume a sports drink.
Sports drinks are VASTLY over consumed on a regular basis. Little Becky or Bobby does not need a Gatorade after their pee-wee soccer match. Give them some fruit and water and they will be fine. And, you certainly don’t need it after a 30-minute spin class.
If you’re going to consume a sports drink then get the one with the least amount of carbs.
Take home point: You probably don’t need to drink a sports drink after you’re done working out, but you do need water!
Enhanced water is water that (generally) has electrolytes added to it and maybe some other things like B Vitamins. This could be the fruit infused water you buy at Whole Foods, or products like Propel, Vitamin Water, etc.
Generally speaking, stay away from 99% of enhanced waters as they have added sugar in them. Some of the enhanced waters have enough sugar to actually make a difference (like some vitamin waters) in your blood sugar and some of them don’t.
Take home point: Drink water. Maybe have some carbs and protein in it if you just did a resistance training session at a high intensity level. Maybe have some electrolytes in it if you just lost a bunch of water.