Staying Hydrated

Nourish - Article 03

Staying hydrated and ensuring your body has the right amount of fluid is crucial for good health. Humans cannot survive more than a couple of days without water and yet we can go weeks without food (even if it doesn’t often feel possible!). Around 60% of the body is made up of water and without fluid, our body would essentially shut down.

Fluid is essential for:

  • Regulating body temperature
  • Transporting nutrients to cells in the body
  • Getting rid of waste from the body
  • Thinking (cognition) and focus throughout the day
  • Contributing to muscle function

At onko, we often see people overlook the importance of drinking enough fluid. It is not uncommon for people to assume their treatment is causing fatigue when actually inadequate fluid intake can be a big contributor.

Why is fluid intake important?

Achieving fluid balance in the body and preventing dehydration is always the goal in nutrition. We lose water constantly through sweat, urine, faeces and breathing. That’s why we must have adequate water coming in to compensate for any water lost.

When the body loses too much fluid due to vomiting, diarrhoea, or excessive sweating, this creates an imbalance in the amount of electrolytes present in the blood.  The balance is controlled by processes involving our gastrointestinal (digestive) tract and our kidneys (the kidneys are involved in excretion of water and the digestive tract is involved in the reabsorption of fluid and electrolytes). 

The trouble is that drug therapy (chemotherapy, radiotherapy), surgery and disease can all affect how well our gastrointestinal tract and kidneys work and can therefore disrupt fluid balance.

At a cellular level, fluid tends to sit inside cells and outside cells of the body in a state of balance. If the balance of fluid is off kilter, for example when there is not enough water in the cell or there is too much sodium in the body, your body’s cells can start to shrink, losing their structure and function and are in danger of becoming damaged.

How to stay hydrated

It’s no big secret. To stay hydrated, make sure you drink throughout the day. Try these simple tips:

  • Keep a reusable water bottle with you so you can keep on track and top up when out and about
  • Drink more fluids in the first half of the day if you find drinking later on leads to frequent trips to the bathroom during the night
  • Keep alcohol to a minimum – the odd glass is fine to be enjoyed but excess alcohol can cause dehydration. It can also play havoc with your immune system, accelerate ageing and increase risk of cancer and other chronic disease
  • Caffeinated drinks, such as coffee and tea, are often thought not to hydrate you because caffeine is a diuretic. However, recent studies have shown that the diuretic effect of these drinks is weak – you don’t necessarily  have to give up your morning coffee.
  • Fruits and vegetables are not only packed with vitamins, minerals and antioxidants but they are also predominately made up of water. For example:
    • Lettuce – 96% water
    • Celery – 95% water
    • Cabbage – 92% water
    • Watermelon – 91% water
    • Honeydew melon – 90% water
    • Strawberries – 91%
    • Peaches 89%
    • Oranges 88%

How much fluid should I drink?

There is no exact science behind this. A common recommendation is 2L water/day. However, it is hard to make exact recommendations as fluid needs are highly individualised according to activity levels, health status, age and environmental temperatures. For most, simply drinking to quench your thirst is enough but you may well need more if you are sweating a lot, have problems with constipation or are exercising regularly. 

If you need something a little more specific, health professionals often recommend 30-35ml per kg of body weight as a guide.

How do I know if I’m hydrated?

Use the colour of your urine as a guide. As a general rule of thumb, the paler the better. However, chemotherapy can do funny things to the colour of your urine so think about other signs of dehydration such as a dry mouth, tongue or lips, dizziness, feeling weak or tired, constipation, dry skin, headache and irritability.

Tip – if you pinch the skin and it stands up like a tent on the back of your hand it could be a sign that you’re dehydrated.

onko success stories

A simple way to start a habit is by linking it to one of your most common daily routines. You could start by having a few sips of water every time you get up and walk around.

For instance whenever Sarah went to the bathroom she would follow it up with a glass of water. “Before long it was ingrained in my daily routine and required little thought”.


Staying hydrated is essential for maintaining good health. Many bodily functions depend on it and without water, your body’s cells could face damage.

You can increase your water intake by introducing habits into your routine, such as using a reusable water bottle, as well as by eating fluid-rich foods. Meanwhile, drinking alcohol dehydrates the body.

You should drink approximately 2L of water a day, or 30-35ml per kg of body weight.

Look out for and know the common signs of dehydration so you know when to rehydrate.