Dehydration and its effects

We are 75% water.  Even a small drop of 1-2% in hydration levels can lead to changes in how we function.  A common situation many of us experience is long term chronic dehydration.  This is where a person's hydration level is consistently a small amount below the ideal.  This can lead to a blunting of our normal thirst response leaving people not wanting a drink, even though their hydration level is not adequate.

Signs & Symptons of dehydration

You may experience the following when you are 1-2% dehydrated:

  • Thirst (not always a good indicator - see above)
  • Reduced appetite (often despite a significant amount of time without eating)
  • Dark coloured urine and reduced output
  • Loss of skin elasticity (pinch the skin on the back of your hand to see how quickly it pings back.  If it's slack and goes back slowly you may well benefit from drinking more)
  • Skin flushing (face & neck)
  • Dry mouth (difficulty producing saliva)
  • Increased levels of fatigue
  • Mild headache
  • Chills
  • Dizziness

We lose water in varying amounts through the day via different routes.  Our main water loss is via urine, faeces, our lungs and skin.  On average we lose around 2500ml of water from our body a day, although being in an air conditioned office, hot weather or exercise can increase the rate at which we lose water, requiring us to drink more than normal.

We often confuse our thirst signal for hunger leading us to eat more than we need.  Try having a drink before reaching for something to eat, it might just do the trick!

Effects of continued low levels of hydration (not drinking enough!)

  • Fatigue - even though you may have slept well
  • Reduced mental clarity / foggy head
  • Loss of concentration
  • Increased blood pressure as blood becomes thicker and the body has to work harder to pump it round the body
  • Increased levels of cholesterol as the body works to prevent water loss from your cells
  • Constipation leading to reduced toxin elimination
  • Joint pain or stiffness.  Cartilage can become weakened and joint repair is reduced.  It can also contribute to disc problems as the discs in your back shrink
  • Weight gain - as your body struggles to eliminate toxins (see constipation) it has to put them somewhere, so it stores them in fat cells.  Your body will not begin to release these stores whilst hydration levels remain low
  • Skin ages more quickly
  • You can become more prone to developing bladder and kidney infections as the normally acidic environment becomes alkaline allowing bacteria to thrive
  • Asthma may become worse as your body restricts your airways to reduce water loss from the lungs
  • Amongst the myriad of effects stress can have on us, it can also increase our need to drink more water, added to which if you aren't drinking enough to start with your level of dehydration increase, causing yet more stress (unfortunately your body doesn't differentiate between types of stress in the way we do and responds in the same way regardless of the stressor!)
  • Increased feelings of depression and anxiety - dehydration may reduce the amount of tryptophan (which is converted to serotonin - our happy hormone) available to the brain
  • Increased levels of inflammation due to higher levels of histamine
  • A diet high in sugar and refined carbohydrates and processed foods increases the need for water as the body tries to dilute levels of sugar in the blood and to get rid of unwanted toxins

Whilst the best thing we can drink is water we also get water from herbal teas, tea, coffee and the food we eat.  Try upping the amount you drink during the day, you may be surprised at how much better you feel!


Maughan RJ.  Impact of mild dehydration on wellness and on exercise performance.  EJCN (92003) 57 suppl 2, S19-S23



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