Keeping Cool & Staying Hydrated - July 22


As I write this, the UK is currently experiencing a heatwave, with some parts of the country reaching temperatures up to 40oC. Most of us are not used to this kind of heat and understandably want to keep as cool and hydrated as we can.


Avoiding dehydration isn’t the only reason to stay hydrated. Our bodies are largely made up of water, which is vital for functions such as regulating temperature, transporting nutrients, removing waste as well as protecting our joints. We lose water every day through the skin, sweat, urine, and breathing. This is especially true on very hot days, as well as days when we are using more energy.


To help you stay cool and keep hydrated here are some quick facts all about hydration.



What happens when we are dehydrated?


Dehydration occurs when we lose more fluid than we take in and can be defined as 1% or greater loss of body mass due to fluid loss. Dehydration is dangerous and can lead to impaired cognitive function, reduced physical performance, headaches, and symptoms of fatigue. Indications that you may be dehydrated include; feeling thirsty, dark yellow, and strong-smelling urine, feeling dizzy or light-headed, tiredness, and a dry mouth, lips, or eyes.


Can you drink too much water?


Extreme overconsumption of fluid is unlikely, as our bodies have systems in place to excrete excess water. However, if these systems become overwhelmed by extreme overconsumption of fluid, it can lead to low levels of sodium in the blood which can have dangerous effects on the body.


Do I need 8 glasses a day?


We are recommended to drink 2 litres of water a day, and this is especially important on very warm days. The amount of fluid we need can vary from person to person, the amount of movement we are doing, how warm it is, as well as age and illness. 8 glasses a day is not a hard and fast rule, however, can be a useful guideline.


Are some foods better than others?


When we are hot, it can often be more challenging to sense or notice our levels of hunger and fullness. When this happens, it’s important to still eat at regular intervals to keep our energy up. Try smaller meals and snacks that involve little preparation. Try cooler foods with high water contents e.g vegetables like cucumber, tomato, and lettuce, as well as fruits such as melons, oranges, and blueberries. Food can provide around 20-30% of our fluid intake, and is an important source of fluid.


What counts towards hydration?


As well as water and food, a variety of beverages can help us with our hydration needs. Tea has a high-water content, and in some cases, can provide some minerals, particularly when combined with milk. Coffee, also combined with milk, can help provide hydration as well as a small number of minerals.


Examples of fluids that count towards fluid intake:


- Water flavoured with fruit and flavourings e.g squash

- Tea including herbal teas

- Coffee

- Milk and milk alternatives

- Fruit juices and smoothies


Is coffee dehydrating?


Caffeine can be found in tea, coffee, cola, and some energy drinks. It has a mild diuretic effect, meaning it can increase our urine output. However, mild coffee consumption does not appear to cause dehydration, as the fluid contained in these drinks seems to compensate for its diuretic effects.


Can water be detoxing?


Over the last few years, there has been a large interest in ‘detoxing’ with many ideas around fluid consumption and its ability to detox the body. The marketing behind detoxing is powerful, with the idea that drinking certain fluids, or eating certain foods can reset or cleanse the body. Luckily for us, our bodies have sophisticated systems to remove toxins every day. Processes in the liver, kidneys, lungs, and gut use a variety of mechanizes to consistently remove harmful substances. It’s important to remember that the phrase ‘detoxing’ when used as a marketing term is not something we need to do via external sources e.g certain drinks, diets, or food products, it’s something we do in our bodies every day.



What are your top tips for staying hydrated in very hot weather?


  1. Keep water near you - whether it’s a bottle at your desk or in your bag or at work. On very hot days, put 2 litres of water in the fridge and drink throughout the day so you know you’re getting enough.

  2. You might find it more challenging to recognize when you are hungry. Keep eating throughout the day to keep your energy up. Try smaller meals and snacks that involve little preparation.

  3. Make it more interesting - flavouring water is a great way to make it more exciting and palatable, this could be with fruit, herbs, or flavored ice cubes.

  4. It doesn’t just have to be water - tea, coffee, and milk can all help towards keeping us hydrated. Try iced teas and coffees for those hot days.

  5. Try eating food with a high-water density e.g vegetables like cucumber, tomato, and lettuce, as well as fruits such as melon, orange, and blueberry.



Hebe Richardson Bsc(Hons) ANutr



(Picture credit: Julia Zolotova)