How dehydration can be disguised as low energy

Do you ever feel exhausted for no reason? Before you blame your sleep schedule or your work load, try this simple tip: to drink more water.

Even slight dehydration can feel the same way low energy levels do, so much so that people often can’t tell the difference between them. 

The problem with dehydration 

The large majority of us don’t drink enough water, in fact most people are around 1-2% dehydrated everyday, although that might not seem like a lot, it’s actually enough to cause a wide range of symptoms, from brain fog and low motivation to headaches and an overall drop in energy.

The interesting thing is that with this level of dehydration we often don’t actually feel thirsty, which is one of the main reasons why it is so important to stay hydrated throughout the day. 

The science behind hydration and low energy:

There's several reasons why dehydration has such an affect on our energy levels:

Blood volume drops 

Our blood is made up largely of water, so when you're dehydrated your blood becomes thicker and there is less of it circulating around your body. This means that your heart has to pump harder to get oxygen around your body. Because oxygen is travelling slower, energy production slows. Think of this like trying to pump syrup through a hose instead of water. 

Lack of oxygen causes brain fog

When your blood volume drops and less oxygen reaches the brain, your neural communication slows. This then causes your brain to work harder, making it a struggle to maintain focus and clarity.

So next time you’re staring at your laptop and your mind goes blank, don’t beat yourself up about it, have a glass of water!

Your cells can’t produce energy efficiently

Your body's main energy currency is something called ATP (or adenosine triphosphate) and your cells depend on water massively in order to make it. Without ATP cells can’t transport nutrients properly, waste removal slows down and mitochondria (your energy factories) work less efficiently. All of these processes cause a dip in energy levels, so even if you're eating well, your body can’t access that energy properly.

Energy boosting hormones are effected

Our level of hydration also impacts several key hormones that regulate our energy levels. Cortisol influences how we respond to stress, thyroid hormones impact how efficiently we produce energy, and ghrelin and leptin control our hunger, cravings, and overall metabolism. 

When we’re dehydrated, the body interprets it as a form of stress. This hormonal stress response can raise cortisol, slow thyroid function, and disrupt hunger signals, making it harder for your body to create steady, sustainable energy.

So the more dehydrated you are, the more tired, less motivated, more hungry, and emotionally drained you’re likely to feel, all because your hormones are working overtime to compensate for the lack of fluid.

Electrolyte Levels Drop 

Electrolytes (like sodium, potassium, magnesium) also play a key role in our hydration levels. Electrolytes are minerals that help your body move water, energy, and messages between cells. Think of them as tiny helpers that keep your muscles working, your brain firing, and your hydration actually getting into your cells.

Without enough water, these minerals become unbalanced, this is because water is what keeps them dissolved and evenly distributed throughout your body. When you’re dehydrated, there’s less fluid in your bloodstream and inside your cells, which means the concentration of these minerals becomes either too high or too low.

This is why you can chug water and still feel tired or dehydrated, without electrolytes, the water can’t get into your cells properly.

This can lead to fatigue, muscle weakness, headaches, irritability, and sometimes dizziness.

However, it’s important to mention that although electrolytes are very important, they’re not something most people need to supplement with all the time. For the average person, electrolytes are mainly necessary during intense exercise, hot weather, heavy sweating, or periods of illness. Your kidneys do a great job of keeping these minerals in balance as long as you’re drinking enough water and eating a varied diet.

Signs you might be dehydrated:

Because mild dehydration doesn’t always cause you to feel thirsty, it’s important to be aware of the common signs that you are. Here are some symptoms to look out for:

• Afternoon energy crashes

• Feeling tired right after waking up

• Cravings for salty or sugary foods

• Headaches or lightheadedness

• Poor focus or irritability

• Darker urine or infrequent bathroom trips

Top tips for staying hydrated: 

Staying hydrated isn’t just about drinking lots of water, there's also some tips to help you stay hydrated as possible: 

• Aim for around 8 glasses of water a day 

• Drink a glass of water first thing in the morning

• Have a water bottle within reach all day

• Add electrolytes if you sweat, drink caffeine, or eat a low carbohydrate diet

• Eat hydrating foods (cucumber, berries, citrus, watermelon)

• Set mini hydration goals (ie 2 glasses before lunch)

• Remember that exercise, heat, caffeine and high-protein diets often require you to drink more

• Aim to hydrate yourself steadily, don’t drink huge amounts at once

• If you’re drinking a lot of water but still tired or lightheaded, you might need more electrolytes, not more liquid.

Final thoughts

Your low energy might not be a mystery, it might simply be dehydration. Try bumping up your water intake this week and notice how your energy, mood, and clarity shift.