Hydration: Why More H20

We’ve all heard the statistics: our body is comprised of 55–75 percent water, blood is 80 percent water, the human brain is 95 percent water, the lungs are composed of nearly 90 percent water…water is not only the body’s most plentiful nutrient, it is arguably its most essential. The development and long-term health of all your body’s systems are highly dependent on hydration levels. While you can survive several weeks without food, only three days without water can cause severe and often fatal health consequences. Optimal health is highly dependent on being mindful of your hydration levels.

Maintaining proper cellular water levels supports the development of the brain, skin, bones, and pretty much every other body system. Adequate water intake has even been shown to naturally suppress appetite, promote healthy metabolism, and support weight loss efforts.1 More concerning are the acute and chronic effects of dehydration. Acutely, short periods of dehydration cause your body to ration water, resulting in short periods of symptoms that may be mistaken for illness such as acid reflux, muscular cramps, headache, nausea, and even allergies. Chronically, miniscule decreases in body water levels can have drastic long-term effects on a number of body systems. In response to cellular water loss, the blood becomes thicker, causing impeded blood flow that results in elevated blood pressure. Furthermore, blood cholesterol rises and your brain actually shrinks. A team of scientists in the UK found that losses in blood water levels as minute as 1.1 percent, something that can occur with as little as 90 minutes of high-intensity physical activity without fluid replenishment, can shrink the brain as much as a year of normal aging or 2.5 months of Alzheimer’s Disease.2 This reduction in mass forces the brain to work harder, leading to struggles in short and long-term memory, problem solving, and other general cognitive tasks. If the condition persists, the results could be fatal.

What constitutes adequate hydration is a simple question without a definitive answer. Few countries have developed water intake requirements, and those that have offer guidelines primarily based on population-level metrics, which are of little relevance to your specific needs3. How much water you need to consume to maintain proper hydration is largely determined by your gender, size, physical activity levels, and diet. Those who are very physically active may need more; if your diet consists of a lot of whole fruits and vegetables then you may require less. The most recent rule of thumb is to divide your weight in pounds by two and drink that many ounces of water daily. The most important thing to remember is that drinking too much water (hyponatremia) is very hard to do, but drinking too little can have drastic consequences. So, just drink.

One of the primary hydration issues comes about because people often replace water with sugar-rich and stimulantinfused substitutes, which have a host of other side effects. That fruit smoothie, while chock-full of vitamins and minerals, is also very high in sugar, predominantly fructose, which in large amounts has metabolic effects similar to alcohol.4 Soda and coffee may be even worse. While the most recent research has dispelled the long-held belief that caffeine is a diuretic,5 it has been linked to everything from raised blood pressure to insomnia and even increased heart attack risk.6, 7 Replace those energy-dense and nutritionally-void drinks with a glass of water.

Drinking enough water to maintain proper hydration levels is quite complex, having both physiological and neurological mechanisms, and intracellular and extracellular compartments. This intricate system requires the coordination of receptors sites all over the body which are linked to neural pathways in the brain that process information. In essence, our thirst impulses are regulated by a negative feedback loop between several internal organs and the brain. The majority of this neurological regulation occurs in the hypothalamus, which constantly monitors blood volume, pressure, and concentrations of sodium within the blood. When excessive fluid loss occurs, as a result of anything from excessive sweating to diarrhea, or blood sodium concentration rises due to eating foods loaded with sodium, the hypothalamus sends messages to encourage increased fluid intake. This feedback loop is a very sensitive mechanism, responding to changes in blood water concentration less than 1 percent. Despite the persistent myth that “if you are thirsty, it is too late,” your body is actually very efficient at regulating hydration. If you are becoming dehydrated and aren’t purposely ignoring the signs, you’ll know it.