Why you are most likely dehydrated and how to fix it:

Summer has arrived. The sun, the blue sky and the warmth finally refreshing our frozen bones from 5 months of winter bitterness. I know I am at least 2 shades browner from a month ago. Similarly some of you are out playing golf three days in a row to make up for lost time or out in the yard embracing nature and gardening. And while some of you will be vigilant about your hydration, chances are most of you will not. I know this because as primary care doctors we see more dehydration related symptoms such as dizziness, fatigue, muscle aches and syncope in summer months than the rest of the year. So, lets go over the importance of hydration and how to keep up.

We are floating water bottles:

Did you know that about 50-60% of your body weight is water!! That is right, while we count calories, stress on our carb, protein or fat intake, most of us pay no attention to our water intake, Despite the fact that we are significantly more water than anything else. In fact most of us can survive without food for many days, but without water we are finished in just a couple of days. Remember those fasting monks? They still drink water.

Most people think of water as the the conduit in their blood vessels. And yes, water is very important for keeping those veins and arteries flowing. But the cells and space between the cells (called the extracellular matrix) are also mostly made of water. Water is the conduit for all cellular activities, so without it the human machinery essentially comes to a halt.

In addition, unlike calories, we do not really store any extra water. The kidneys are a very efficient organ system that control the amount of fluids in our system. Too little, and your urine is small and dark, too much (like after a couple of beers) and your urine is large and dilute.

All put together, this is why you will suffer from dehydration much faster than starvation;

• You are mostly made of water

• Water is the conduit for all cellular activities

• You do not store excess water and

• You are continuously losing water through insensible water losses

Thankfully we have potent thirst sensors to prevent us from reaching the abyss stage of death from dehydration. But it turns out that our thirst is not as great when it comes to mild to moderate dehydration. So, you may be walking around all dried up without knowing it.

Some common symptoms of mild to moderate dehydration are :

1. dizziness, special with standing

2. lightheadedness

3. fatigue

4. muscle cramps

5. recurrent kidney stones

6. elevated heart rate or abnormal elevation with mild activity

7. dark or yellow urine

And while most of you may think of sweating and urinating as the main sources of water loss, we can actually lose a significant amount of water through "insensible water losses."

Insensible losses are referred to water losses that happen without our knowledge or control. Skin and lungs are the two main sources of insensible water loss:

Skin: While dogs pant to keep cool, we sweat to keep cool. You probably already knew that from very hot humid summer days and your workout days. Sweating is essentially nothing but a cooling system. But you also sweat at a much lower but steady rate during warm days even if you don't necessarily notice it. You do not need a drenched shirt for proof, the fact that you are not dying of heat exhaustion while playing golf or gardening in summer days is proof that you are sweating. Want more proof, next time you sit out in the sun for half an hour lick your arm, pretty salty!

Breathing; have you ever blew on your sunglasses to get that mist, and then wipe it on your shirt to clean it? Well, that mist is nothing but water vapor. Your lungs lubricate the flow of air by moisturizing the airways with water vapor. So every time you exhale, you are blowing out water in addition to other waste gases. Now, if you are doing anything active and therefore breathing more frequently or heavily, well then guess what, you are also blowing out more water.

Fun fact: Fever is another notorious water loser: when you have a fever you sweat to reduce your body temperature and you breath faster because fever increases your metabolism, generating more carbon dioxide that you need to exhale.

The water loss via the skin and lungs are not regulated, meaning that your body has no way of adjusting amount of water content based on your whole body water volume. However, as you get more dehydrated water is shunted away from the none essential organs (skin) to the core essential organs (heart, liver, lungs, kidneys). This will hinder your ability to cool off in hot weather. I knew I am dehydrated on my morning run yesterday when after 30 minutes of running in humid 80 degree weather I had barely broken a sweat.

This becomes a problem if you are exposed to the heat for too long: excess heat causes your body temperature to go up, but you are dehydrated so you can not sweat and cool off, internal temperature continues to rise until its too hot for the organs to function, a vicious cycle: this in short is heat exhaustion and why every year people die from it.

On the other hand the kidneys are extremely sensitive to whole body water content. After all one of their main jobs is to regulate the fluid balance. The kidneys have various pressure receptors in the arteries that feed them. The pressure in these arteries is an accurate indicator of total volume status. So, if the pressure drops the kidneys know the tank is empty and they retain more fluid (notice how you pee so little when you wake up in the morning or end of a weekend when you have been out all day and barely drank). On the other hand if the pressure goes up, after a couple of beers, the kidneys know there is too much in the tank, and the valves loosen, you better find yourself a bathroom quick. There are some other subtle ways that the kidneys monitor hydration status via monitoring electrolytes (mostly sodium), but that is beyond the scope of this blog.

So, now comes the big question. How much should you drink. And what should you drink.

The second question is much easier, so lets get that out of the way. Any fluid besides alcohol counts. Water, any beverage (even coffee) and fruits which are mostly made of water all count towards your daily hydration.

Fun fact: Alcohol tends to have a very potent diuretic effect (diuretic is medical term for pee inducing), so what you drink you pee out.

How much you drink depends on many factors. Your gender, age, size and lifestyle. But in general, for most adults of average height and weight, your total water intake should be around 64 ounces (hence the famous 8x8 rule: 8 glasses of 8 ounce water). This is. enough fluid to replace your total daily loss from insensible losses and the kidneys. But if you are an active person, been outside most of the day, exercise or even are sick you need extra fluids.

For active people (I am talking construction worker, waiters, flight attendants) I would simply add 2-3 glasses of 8 oz water to your baseline. Unless you are sweating excessively for more than an hour, you do not really need to add electrolyte solution, you will get enough electrolytes from your diet.

For athletes, or if you are outside doing something active for a prolonged time, you have two options:

1) a rough estimate: drink an additional 4 oz for every hour you are outside, best done by having a water bottle with you and sipping on it periodically as you work/exercise outside.

2) a more accurate way is to do a weight test. Simply weight yourself with no clothes on before your activity, then weight yourself after your activity, find out how much weight you have lost. Add to this number the amount of water you consumed during your activity. That is the grand total amount of water you have lost and need to replace ( in addition to your total daily intake). For me, I loose 2 pounds in cold months and 3 pounds in summer months per hour of running. I also drink about 16 ounces per hour during my runs. So, in a one our run I lose about 2.5 pound (40 ounces), plus the 16 ounces I drank, my total water loss from my run is 56 ounces (or 1.6L).

The best way to replace your water loss from activity (sweat) is half water and half sport electrolyte solution. This is because your sweat is made of water, salt and other electrolytes such as potassium and magnesium, but there is more water than electrolytes per unit of sweat. So a half water and half electrolyte solution will be a good estimate. My favorite brand of electrolyte powder is Scraitch which you can get from Amazon, but there are other excellent brands as well.

For those who want an even more precise measurement of their sweat rate and content, you need to get an actual sweat test where your sweat is examined after a. certain amount of activity. These are usually done at sports labs or universities.

So, drink up before you dry up.