What does dehydration actually feel like, and how bad is it for you?

What does dehydration actually feel like, and how bad is it for you?

Guides & Advice

Words Joe Hitchcock

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The science of dehydration, the risks of being dehydrated, and five tips to stay hydrated.

One of the (many) odd things about us human beings is that we drink when we’re not thirsty. Scientists call it non-regulatory drinking. From enjoying coffee for the caffeine, to whole parts of our culture wrapped around social drinking, the way we drink creates a separation between drinking and hydration. All of which means, when you’re looking to build a healthier relationship with hydration, it can be hard to get clear on what, when, and exactly how much you should be drinking.

What does hydration really mean?

For the body, hydration is all about maintaining an essential balance between water and minerals on the cellular level. Given water can comprise up to 75 percent of your weight, your body takes this job seriously, with a mound of sensitive detectors for different organs linked by extensive neural pathways.

The benefits of hydration appear across the body, from temperature regulation to joint health, but they’re especially apparent in the skin. Hydrated skin is more elastic in the epidermis layer and, as a result, smoother. By maintaining a good water balance, some researchers believe that the risks of several diseases, infections, kidney stones, and possibly even cancers might be reduced.

For the mind, hydration is important for feeling lucid and on top of things. Basically, if you’re thirsty it probably means you’re less alert, and more prone to mood swings. Researchers have suggested this is because dehydration acts as a stressor on the brain, competing with and drawing attention from other cognitive processes—so it pays to drink up. That said, there are a wide range of normal fluid intake requirements, and the amount of water you need increases and decreases with exercise, perspiration, and outside temperature.

When does dehydration begin, and how does it feel?

The first signs of dehydration are mental, with decreases in alertness and the ability to concentrate. Sufferers of mild dehydration may also experience tiredness and headaches. Apparently, these effects are something most of us feel rather a lot. According to a 2015 study, less than one in four UK adults drink water on a regular, daily basis. Even more alarmingly, 15% admit to consuming more alcohol than water. As dehydration continues, blood volume begins to reduce, making the blood thicker, which in turn increases heart rate. This chain reaction causes the body to find it more difficult to lose heat, which is why the symptoms of heatstroke can increase so rapidly. When the body is overheated and lacking water, exercise is likely to become more difficult, clear thinking gets harder, and you may feel more emotional.

In everyday life, the risks of short-term dehydration are mostly connected to performance. For example, McGregor et al. (1999) tested the effects of dehydration on footballers, finding that dribbling skill decreased by around five percent when drinks weren’t on hand. Dehydration also increases the risk of cognitive impairment, which is why some studies have found that dehydrated driving is as dangerous as drunk driving.

How to tell if you’re dehydrated

You’re thirsty!

Because it can be easy to ignore the feeling of needing a drink, it’s also easy to disassociate thirst from genuine need. But it’s a legitimate indicator of dehydration, as the body can only tolerate 1 to 2 percent of water loss before presenting problems.

Brain fog

Water is essential for delivering nutrients to the brain and removing toxins. A hydrated brain can efficiently remove toxins—thus when dehydration sets in, so do feelings of sluggishness.

Yellow pee

The kidneys make urine to remove waste from the bloodstream. Human urine is mostly water (91% to 96%), with the rest made up of solutes like creatinine and the yellow-pigmented chemical urochrome. The less hydrated you are, the more concentrated the urochrome, the more yellow your urine.

How do I stay hydrated, then?

As a general guide, Dr. Seifter of Harvard Medical School recommends drinking 1 to 1.5 litres of water on a normal day—but not all at once. “The kidneys lose some ability to eliminate water as we age. It's important to stay hydrated gradually, throughout the day”. When you do get thirsty, drink water in small amounts. Pushing fluids can risk messing with the balance of sodium and other vital minerals in your cells.

If you want to stay hydrated throughout the day, it might be smart to invest in a good quality flask, made from stainless steel/aluminium or BPA-free plastic. Convenient to carry, it will allow you to take water everywhere with you. On the go? Most cafes and stores will be happy to fill you up!

Water, though, is not the only way to stay hydrated. Your diet plays a huge role in fighting dehydration. Here are some more tips: first, stock up on cucumber and celery - those slices in your gin or that stick in your Bloody Mary are not just some strange kind of decoration. At 96.7 and 95.4 percent water respectively, these foods are probably more hydrating than the cocktails they accompany. Then, avoid processed foods: things like cured meats and snack bars are often created by using salts to increase the food’s lifespan (salt reduces the water they contain). Also, don’t neglect your fruit intake: at 93% water, watermelon is arguably the tastiest rehydrator, but other good candidates for edible hydration include strawberries and grapefruit (bitter, yes, but worth it).

Stay hydrated