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Myth Monday: You Can Never Drink Too Much Water



Walk into any well-known fitness franchise and you’re bound to see one or more of the following: someone on a machine for ten minutes doing everything BUT the proper movement; a morbidly obese individual slowly pedaling a recumbent bicycle while enjoying their daily Starbucks “Caramel Snickerdoodle Macchiato”; and AT LEAST one person walking around with a gallon jug of water, chugging between sets like their life depends on it.

Sometimes I ask myself, “How can all of this be possible? Where did people learn these things?” The answer is simple: they didn’t. If you have been educated in health or exercise, the answers often will be obvious. For example: “That machine is terribly designed, it’s no wonder why people use it incorrectly.” Or: “A calorie deficit must be present in order to lose fat.” But why is there always “The gallon of water guy”? Where did this gallon-of-water idea come from? Many times this person appears to be fit and educated on their exercise program. Maybe they think that since our muscles are about 75% water by weight, drinking as much water as they can will help them build muscle? Maybe they just saw a very fit, muscular person chugging water straight from the jug one day and decided to give it a try? Who knows? But if YOU ever have tried to “drink more water” as one of your specific fitness goals (other than trying to suppress hunger by filling your stomach), I ask you, why? I know if you think about it long enough your answer will be, “I don’t know. It just seems healthy.”

The Facts

The chance that you, as an American, are consistently dehydrated is VERY slim. When we are thirsty, we drink. I am not saying dehydration is not possible or should be ignored, but if you are someone who always worries about not drinking enough water, you are more likely to overhydrate than to become dehydrated.

When it comes to hydration, there is no simple formula that works for everyone. You most likely have heard the rule, “Drink eight 8-ounce glasses of water each day.” Although no hard evidence supports this rule, it’s easy to remember and will hydrate most individuals more than adequately. The reality is the recommended intake of water varies greatly from person to person. Some of the most common factors that may alter these requirements include, but are not limited to, the following:

Height and Weight: larger, more metabolically active bodies require more water.

Activity Levels: exercise and other activities of daily life that cause perspiration need to be offset by an adequate amount of water intake.

Environment: hot or humid weather can make you sweat and will require an additional intake of water.

Altitude: altitudes greater than 8,200 feet may trigger urination and more rapid breathing. This will cause an individual to use up more of their fluid reserves.

Health status: Having a fever, vomiting or diarrhea will cause your body to lose additional fluids. In these cases you should drink more water. However, some conditions such as heart failure and some types of kidney, liver or adrenal diseases may impair excretion of water and require that you LIMIT your fluid intake.

Pregnancy: pregnant women or those who are breast-feeding need additional fluids to stay hydrated (10-13 total cups/day).

I want to reiterate it is VERY important to stay hydrated, BUT often we forget how much the foods we consume aid in our hydration status. On average, consumption of our everyday food provides about 20% of total water intake. Food like fruits and vegetables can be more than 90% water by weight.

We also fail to realize beverages (other than pure water) are composed mostly of water. Milk, juice, coffee, tea, soda…even beer and wine can contribute. Though these beverages shouldn’t be the majority of your daily total fluid intake, realizing that they contribute to hydration is important.

Can I drink too much water?

Believe it or not, forcing yourself to consume large quantities of anything can be unhealthy or dangerous, even water. Overhydrating, though rare, can cause a dangerous condition called “hyponatremia”. Our kidneys are responsible for controlling the amount of water, salts, and other solutes leaving the body. When a person drinks too much water in a short period of time, the kidneys cannot flush it out fast enough. Sodium helps to regulate the amount of water that’s in and around your cells. When our kidneys are unable to flush out this excess water at a fast enough rate, these sodium levels become diluted. As a result, excess water is able to leave the blood and enter the cells causing swelling.

Most cells have the capability to stretch and expand but it’s not always the case. Brain cells are tightly packed inside of our rigid, bony skull. This space already is shared with blood and cerebrospinal fluid so there is VERY LITTLE room for cells to expand and swell. Overhydrating to this point is rare, but this water/sodium imbalance can cause brain edema (swelling) and become disastrous. Swelling of our brain cells can cause seizures, comas, respiratory arrest, brain stem herniation, or even death.

In 2002, Heinz Valtin, a kidney specialist and author of two widely used textbooks on the kidneys and water balance, decided to test the commonly known 8 x 8 water recommendation. He concluded that no scientific studies support the 8 x 8 rule (for healthy adults living in temperate climates and performing mild exercise). In fact, consumption of this much water each day could precipitate hyponatremia and exposure to pollutants. The rule also makes people feel guilty for not “drinking enough”. Vatlin stated that “not a single scientific report published in a peer-reviewed publication has proven the contrary.”

So how much water should I drink?

Bottom line: drink when you are thirsty, not because you think you need to. Though specific guidelines for water intake during exercise DO exist, it varies greatly upon the duration and intensity of exercise, environmental temperature, and the size of the individual. We get far too caught up on “sipping” all day (even if we are not exercising). When it comes to your everyday hydration, drink to your thirst. It’s truly the best indicator.

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