Everyone knows that water is essential to wellness because it is what the body is primarily composed of. The proper balance of water and electrolytes determines how our bodies function, including the responses of our nerves and muscles. Water removes metabolic waste, controls body temperature, heart rate and blood pressure and maintains a balanced metabolism. Without it, our bodies begin to shut down. But how much do we need, how can we work that requirement into our daily lives, and how can we check our hydration levels? Let's dig in.
HYDRATION AND PERFORMANCE
Everyone knows that both urinating and sweating results in loss of water, but there are other ways in which our fluid levels are reduced throughout the day: in bowel movements, by breathing (we exhale water vapor; the exact quantity depends on the humidity level of our environment), in the processing of medications, via a moisture-deficient diet (dry foods require more water to process and store nutrients) and via heart rate and breathing related to stress. We are constantly losing water, which is why we need to replenish.
In both anaerobic and endurance exercise, athlete hydration levels are critical to performance. It is crucial for anyone engaging in intense and/or prolonged physical activity to go into said activity properly hydrated, and to develop a plan of fluid replacement based on their individual fluid loss ratios.
The body's work capacity drops in direct relation to the degree of dehydration an athlete suffers. Aerobic activity sees a sharp decline in performance whereas sports or exercise requiring muscle strength and endurance see a variable decline.
The primary causes of performance decline include reduction in blood volume, decreased skin blood flow, decreased sweat rate (therefore decreased heat dissipation and increased core temperature), and increased rate of muscle glycogen use. The fluid in your body is the highway, and with less of that medium available your body has to work harder to circulate the necessary fuel to the active muscles and remove the cell waste.
HOW MUCH WATER DO I NEED?
Ever hear the old "8 8oz glasses of water daily" prescription? This is a good rule of thumb, but it is nevertheless a generalization and doesn't hold true for every person due to differences in activity level, environment, body size, diet, medications and medical requirements, etc.
The easiest way to tell if you are properly hydrated is the urine color test. A properly hydrated individual goes to the bathroom every 2-4 hours.
Athletes, fitness enthusiasts and those who work outdoors require more water than someone with an office job and sedentary lifestyle. The exact amount required differs by individual for this population, too.
The biggest problem especially for those new to fitness is knowing when to hydrate. Oftentimes they gauge whether or not they need water by their thirst. The problem is that your body's thirst mechanism is turned down during exercise, so if you get thirsty while working out you are actually currently dehydrated and need to drink some water immediately and sip on it as you continue your activity, whether or not you are thirsty.
A good way to gauge how much fluid you lost during your workout is to weigh yourself directly before and immediately afterward. As you recover you will continue to lose fluid through sweating and urination. You will need to replace 125-150% of the fluid deficit in the subsequent 2-6 hours after exercise. 1 pound is 16oz, so if you lost 2lbs during exercise you will need to drink 40-48oz of water, which is 125-150% of the fluid you lost while working out.
If you are not exercising but still find that you don't get thirsty very often, your thirst mechanism is not functioning properly. This article has a great suggestion for how to kick it back into gear:
Get one of those small, Dixie paper cups, or a shot glass. Fill that cup up with water and drink three to five shots in quick succession, one right after the other. Wait 30 minutes then do that again. Do that in the morning and in the evening, and by the second day, you’ll probably start noticing your mouth getting dry more frequently throughout the day. Do that routine for a week, and your thirst mechanism should be in full functioning order.
Plain water is the best source of hydration, but there are other ways to meet your requirements including eating foods high in water content or consuming other beverages. Be aware that any alternate hydration source potentially contains sugar and calories. For some populations such as endurance runners this is advantageous, but for an average person doing an hour-long workout to lose weight, the best possible source of hydration is the one to stick to. Plain water contains zero calories, zero sugar, and is most readily absorbed by your body. Also note that you will absorb less water from alternate hydration sources; a cup of fruit juice or a smoothie is not equivalent to the same size cup of plain water.
Alternate hydration sources include:
Caffeinated beverages have a mild diuretic effect which causes you to urinate out some of your water, so the widespread rule of thumb is that for every caffeinated beverage you consume you need to drink an equal portion of plain water. Alcohol is a diuretic as well as typically being high-calorie and full of empty carbs. It is best to drink responsibly and limit your consumption. The 1 to 1 ratio of diuretic to plain water also applies to these beverages.
WHEN SHOULD I HYDRATE?
The easiest answer to this question is ABD: Always Be Drinking. If you drink a large volume of water at one time, your body will be unable to absorb it all. Sipping on your beverage is the best way to ensure proper absorption as well as preventing major bouts of thirst.
To ensure that your sleep is not interrupted, it is recommended that you finish any beverage you're working on at least two hours before bed. That way you have enough time to process it before settling in for the evening -- disturbing your rest by having to go to the bathroom every few hours overnight is counter-productive.
WATER AND WEIGHT LOSS
Maintaining proper hydration can assist in weight loss. Water is an appetite suppressant. Drinking before you eat helps make you feel fuller, thereby reducing how much food you eat. According to WebMD, drinking before eating results in an average reduction in intake of 75 calories per meal.
Focusing on your fluids, if you can swap out calorie-filled drinks for plain or infused water, that change alone can potentially result in weight loss depending on how many calories you drink. You can easily use a tea infuser to add cucumber slices or fruits to your water to give it natural flavor without the artificial sweeteners or food dyes. You could also grab a water infuser bottle or pitcher for the same purpose, or just add a slice of lemon.
Drinking it cold helps to slightly boost your metabolism as your body has to work harder to to warm the water up. This boost is very slight, but getting in the habit of consuming cold water also aids the body's absorption rate. Optimal temperature for maximum absorption has not been ironed out but studies indicate 45-55 degrees F to cause the water to empty from the stomach more quickly into the small intestine, where absorption happens much more rapidly.
CAN I DRINK TOO MUCH?
YES. Overhydration, or hyponatremia, occurs when the concentration of sodium in your blood is abnormally low. When you drink too much water, you throw off your electrolyte balance. Since electrolytes regulate the amount of water in and around your cells, without the proper balance your cells begin to swell.
Some of the symptoms of hyponatremia include headache, confusion, nausea/vomiting, loss of energy/drowsiness/fatigue, muscle weakness, spasms or cramps, restlessness or irritability, and eventually seizures and coma.
An easy way to prevent exercise-related hyponatremia is to consume sports drinks (which include electrolytes in them) during demanding and/or prolonged physical activities where you sweat and expire an excess of water, and checking your hydration level via the above urine chart. If your urine is in the safe range and you are not thirsty, you are getting adequate water.