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The dangers of dehydration

Patsy Westcott / 19 June 2018 ( 15 July 2019 )

Staying hydrated is vital, especially when the weather is warm and we’re out and about much more. Find out how to maintain optimum levels.

Water with cucumber
If you don’t like plain water, add some zing with lemon slices or cucumber.

Our bodies are between 50% and 75% water, which is needed to carry nutrients to our organs and waste products away from them, to help regulate body temperature, lubricate our joints, keep our brains sharp and much more.

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What is dehydration?

We naturally lose around two-and-a-half litres of water a day through sweating, breathing, urine and faeces. We also lose electrolytes – think calcium, potassium, magnesium and sodium – which regulate the flow of water in and out of our cells and trigger the nerve impulses that keep our hearts beating, our lungs pumping air in and out, and our brains firing on all cylinders. Dehydration happens when we don’t drink enough to replace the fluid that we are losing.

How much water do we really need to drink?

What problems can dehydration cause?

Even a small shortfall in water can lead to a downturn in mood and a foggy brain, according to a research overview published in 2017.

Persistent dehydration can contribute to kidney stones and complicate other health problems. For example, dehydration can increase the risk of falls and lead to an increased risk of post-operative complications.

Recent studies also suggest that not drinking enough plain water can increase the risk of insulin resistance (when the body produces but doesn’t use insulin properly), fatty liver and Type 2 diabetes. All good reasons to keep up those H2O levels.

Strategies to avoid dehydration

Dehydration and age

As we get older, we’re more at risk of dehydration due to…

  • An increased proportion of fat to muscle (muscle retains water better than fat) leading to a decrease in total body water.
  • A downturn in kidney function – they don’t respond so well to mild water deprivation.
  • Diminishing thirst sensation – we’re no longer nudged to drink until we’re already dehydrated.
  • Certain medications and conditions such as diabetes, which affect water balance.
  • Creaky joints and loss of mobility, due to conditions such as Parkinson’s, can make it hard to reach for or hold a glass.
  • Limiting water intake, especially if we have bladder issues, for fear of being caught short if there’s no loo nearby or to avoid having to get up at night.

Five ways to top up

1. Choose water – tap, bottled, still or sparkling – is your ‘go to’ for staying hydrated. And the bonus is it contains no calories or sugar. Don’t like plain water? Add some zing with lemon slices, cucumber, borage flowers, sliced ginger, lemon grass or strawberries.

Which water is best - tap or bottled?

2. Water doesn’t all have to come from drinks. Around 20-30% can come from foods. Foods with a high water content include watermelon (91% water per 100g), courgettes (92%), lettuce (94%), cucumber (95%), celery (96%), strawberries (90% ) and even hard-boiled egg (75%).  

The 10 most hydrating foods

3. Drinking little and often is better than glugging down half a litre at a time.

4. You need more water when it’s hot and dry – so don’t forget to keep a water bottle with you if you’re heading out to the Med or other hot-weather holiday destination.

5. Use an app such as Fitbit, My NetDiary or My Fitnesspal to remind you to drink often and stay on track.

The best diet and nutrition apps

Are you dehydrated?

Watch out for these dehydration signs

  • Constipation
  • Dark urine (healthy urine is pale or straw-coloured)
  • Dry, parched lips
  • Sticky saliva
  • Few or no tears when crying
  • Headache
  • Thirst
  • Dizziness
  • Tired, aching muscles
  • Fatigue/sleepiness

Note: Severe dehydration can cause confusion, seizures and even death.


The opinions expressed are those of the author and are not held by Saga unless specifically stated. The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.