We’ve long been told to “drink plenty of water.” Whether we are playing a sport, exercising, sick from a flu or cold, or just because it’s hot out, advice to drink lots of water is obligatory. Preventing dehydration is very important, indeed. Not drinking enough water over the short term causes headaches, dizziness, fatigue, low blood pressure, and in extreme cases it can even cause delirium, unconsciousness, or death. Chronic dehydration can cause obesity, digestive issues, premature aging, chronic fatigue, constipation and more. Staying hydrated makes every bodily process work its most efficiently. We will feel better, our organs and skin will be healthier, and our brains and muscles will perform better. What is much less understood is that drinking too much water causes problems of its own. Excessive water consumption triggers the body to flush the system. In doing so, it flushes out valuable electrolytes and minerals. While this normal ebb and flow of taking in minerals and then flushing them is not usually an issue, if we drink too much and subsequently flush too much water, we lose too many electrolytes and minerals, causing imbalances and deficiencies, which can minimally make our bodies operate less efficiently and maximally cause serious health issues. Also, when we drink more water than we need, the body tends to flush more water than we drank in anticipation of continued intake, which also causes dehydration. However in this case, not only are we dehydrated, but also depleted of minerals and electrolytes. So, while it is important to drink enough water to stay hydrated, there is an upper limit at which point it becomes detrimental. How much we need is dependent on a number of factors such as activity level, how much we eat, room/outside temperature, and much more.
Risks of too much water
The human body will, naturally, do an excellent job to maintain proper hydration on its own. Don’t drink enough, and the body reacts by conserving water. Drink too much, and the body will flush the excess. The body has learned over thousands of years of evolution how to manage the much more common condition of water scarcities. We are, however, far less prepared to properly manage self-inflicted situations of drinking excess water. When we drink a lot water in a short period of time, the body has a natural volume response that flushes water from the system, but once it starts, it keeps going, and often flushes more than it takes in. This is why drinking too much water also causes dehydration. This is not unlike an allergic reaction, another body system flaw. In an allergic reaction, the body’s immune system has an over-reaction to a normally harmless substance. Basically, the immune system is confused, and the result can be as mild as a sneeze or a catastrophic as death in the case of anaphylactic shock. When we drink too much water, the body attempts to correct the problem, but ill-equipped with a system to properly regulate electrolyte balance, it over-reacts by flushing too much water and along with it too much electrolytes, leaving us in an unhealthy state.
How much should we drink?
The ubiquitous recommendation of 8 glasses per day is a decent guideline, but really doesn’t take any variables into account, and there a lot of variables. Body size, activity level, how much and what kind of food you eat, heat, humidity, and how much you sweat are the main factors, but there are many more. It really would be impossible to assign a quantity without knowing these variables. A recent study found that 1/3 of Boston Marathon runners were drinking too much, most likely as a result of following the advice that more is better. This, of course, can cause their performance to suffer just as much or more than had they not drank enough. As a rule of thumb, if you follow your thirst, you are going to end up taking in about the right amount. Drink when your body tells you to and maybe a little extra, but not much. Be sure not to binge on water when you are thirsty. A glass or two will suffice, then drink more later if you are still thirsty. Much like food, it is better to drink smaller amounts more frequently as opposed to drinking copious amounts in one sitting then not drinking again for hours. A good strategy would be to figure out about how much you drink on a regular day or better yet, over the course of a week. This will give you a good baseline number of how much you consume. Then, as variables present themselves at a later date, such as a day of heavy exercise or a lot of time spent in a lot of heat, you can make adjustments to add the appropriate amount to your diet.