By far, the most abundant molecule in the human body is water. It performs a wide range of critical functions, from maintaining body temperature to transporting important elements like hormones, vitamins, and minerals, to lubricating areas of the body like joints, eyes, and intestines. As you age, the percentage of water in your body decreases. At birth, about 70% of your body weight is water. By the age of 40, it decreases to about 60% (for men) and 52% (for women). By 60, it declines even more to about 52% and 46%, respectively.

Thirst: It Does a Body Good

The amount of fluids in your body is constantly changing. In general, your body takes in fluids through what you eat and drink and expels them through sweat, urine, and other bodily functions. You can only survive a matter of days without water. As you become dehydrated, your survival instincts begin to kick in. The primary thirst center in the brain is the hypothalamus, which also regulates body temperature, sleep, and appetite. The hypothalamus constantly monitors input from your body regarding the concentration of sodium and other key elements in your blood, as well as the volume and pressure of your blood vessels. When the hypothalamus senses insufficient fluid levels, it sends out a “thirsty” message that it’s time to drink. It also sends a signal to your kidneys to start concentrating urine (by reabsorbing water) so that fewer fluids are lost that way.

Older Adults Have a Drinking Problem

For reasons that are not yet fully understood, the body’s thirst messaging-system worsens with age. As a result, older adults may not feel thirsty even though they are dehydrated. In addition, the kidneys’ ability to remove toxins from the blood also decreases over time, requiring more water for them to be able to do their job. Consequently, more fluids are expelled from the bodies of dehydrated older adults than from their younger counterparts.

In addition, there is a natural loss of muscle mass that occurs with age – approximately 3% to 5% per decade beginning at about age 30. As muscle mass decreases, the amount of water the body can store also decreases because muscles are a meaningful holding area for water molecules.

Apart from these age-related factors, older adults are also more likely to be taking medications that increase the risk of dehydration. For example, diuretic medications that are often prescribed to treat high blood pressure or heart failure may cause you to become dehydrated.

Regardless of the cause, a 2015 study determined that 20% to 30% of older adults are chronically dehydrated. Another study found that 37% of older people admitted to a hospital were dehydrated. Finally, a U.K. study of older adults in residential care facilities concluded that 46% had impending or current dehydration.

The Dangers of Dehydration

Dehydration occurs when fluid levels in your body are insufficient to meet the needs of your cells and blood vessels. Regardless of age, even mild dehydration can result in confusion, fatigue, loss of strength, reduced coordination, and decreased cognitive function. Symptoms of mild dehydration include dry mouth, being tired or sleepy, decreased or more yellow urine output, headache, dry skin, dizziness, and few or no tears. Symptoms may worsen quickly, however, which would be indicative of severe dehydration. Signs that you are severely dehydrated include either no urine output or urine that is concentrated (deep yellow or amber in color), dizziness or lightheadedness that does not allow you to stand or walk normally, a drop in blood pressure when trying to stand after lying down, rapid heart rate, fever, lethargy or confusion.

Recommended Levels of Hydration

Older adults literally don’t get the memo that they are thirsty. Park City Attorney Greg Bishop suggests that retirement is the perfect opportunity to proactively establish a hydration strategy. He explains that as a general rule, drinking too much is not a problem because excess fluid is released through urine. That said, if your urine is completely clear, or if you urinate more than 7 times a day, you should dial back your fluid intake.

While there is broad agreement about the need to avoid dehydration, the recommended amount of water that adults should drink each day is literally all over the map. For example, the American and Canadian guidelines have the highest recommendations. Specifically, they suggest that adults should have a total daily water intake (from food and all beverages) of 3.7 liters (15.6 cups) for men and 2.7 liters (11.4 cups) for women. In contrast, the Australian and New Zealand guidelines are lower at 3.4 and 2.8 liters per day (14.4 and 11.8 cups, respectively). The European guidelines are lower still at 2.5 liters (10.5 cups) for men and 2.0 liters (8.5 cups) for women.

In addition to these government recommendations, there are also a number of apps (many of which are free) that calculate daily hydration recommendations based on various factors such as gender and body weight. Most of these apps send alerts to your smartphone to remind you when it is time to drink more water.

Regardless of which guidelines or app you follow, there is general agreement that you are well-hydrated if your urine is light yellow (excluding color changes attributable to foods, medications, vitamins, and health conditions). There is a similar consensus that it is better to sip water continually throughout the day – especially with meals – rather than pounding down a large glass of water at one time. Finally, you should increase your normal water intake when you exercise and when the weather is hot.

About Greg Bishop, Attorney

Greg Bishop has spent the past 30 years working closely with C-Suite executives and the Board of Directors of both public and private companies. He has been the executive in charge of legal, compliance, and HR matters. As he approaches retirement, he is shifting his focus towards personal development and helping people live their lives to the fullest.

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