What to eat and drink in a heatwave

What to drink in a heatwave

How much water should I drink?

Those living in temperate climates typically lose between 1½ and 3 litres of fluid a day through sweating, breathing, urine and faeces. This means on regular days we should be drinking about six to eight glasses of water or other hydrating fluids. The good news is you can hit this quota through milk, sugar-free drinks, tea and coffee, as well as trusty water, but remember caffeinated drinks have a diuretic effect, making you lose more fluids, so try keeping these to a minimum. Fruit juice and smoothies count too, but they should be limited to one 150ml glass daily because of the natural ‘free’ sugars they contain.

It’s not a case of ‘one size fits all' when it comes to water intake. Our specific needs vary depending on age, size, sex and amount of physical activity we do, as well as environmental factors including the temperature and humidity, both of which speed up the water lost through your skin.

Should we drink more in hot weather?

Higher temperatures and humidity increase the speed of evaporation from the skin which means we sweat more. This means we need to replenish our fluid levels more often. How much more you need really depends on your personal circumstances as well as how active you are.

If you do regular exercise, this doesn’t have to cease during hot weather. Try sports drinks, which are formulated specifically to promote fluid uptake, making them more hydrating than plain water.

Can you drink too much water?

It is possible to go the other way and drink too much, although for most people with healthy kidneys this will be managed by urinating more frequently. Too much water consumed in a short space of time may lead to the kidneys being unable to maintain electrolyte balance, so the blood becomes very dilute. This has an effect on how our body functions – for example it impacts blood pressure. Hyponatraemia is a condition where sodium levels (electrolytes) fall dangerously low, one reason for this is taking on more water. Athletes who participate in endurance events and take on too much fluid may be at risk of this condition, although hyponatraemia may also occur in those on prescribed medication such as diuretics and certain anti-depressants.

Read more about how to stay hydrated during exercise.

There may also be a medical reason why a person retains more fluid, it might be the result of an existing kidney or heart condition. If you have a health condition or you are experiencing water retention, see your GP for advice on how much water is right for you.

What to eat in a heatwave

Which foods are the most hydrating?

What we eat may account for around 20-30 per cent of our fluid intake, and there are some foods that may be more hydrating than others. Especially useful are:

Strawberries
Cucumber
Courgettes
Celery
Lettuce
Melon

Discover more hydrating foods.

Recipes with high fluid contents may help towards hydration levels, too. Soups, stews and porridge are all good examples, and of course they can be made less wintery with the right seasonal ingredients. Try some of our summery recipes below:

Our top summer soup recipes
Summer chicken & basil stew
Summer fish stew with rouille
Summer braised chicken with tomatoes
Porridge with blueberry compote
Cardamom & peach quinoa porridge
Green rainbow smoothie bowl

Can food and drink help us cool off?

Ice-cold lollies, slushies and ice cream might seem like the obvious choice when you want to cool off, but the initial cooling effect may be short-lived. That’s because eating food leads to an increase in temperature as the process of digestion is heat-generating. This combined with the rapid cooling initiated by cold food and drinks means your body over-compensates by increasing your core temperature. So, you may actually end up feeling hotter than you did to start with!

Drinking something hot on a sunny day might feel like the least appealing thing to do, but warm drinks can help regulate your body temperature. As your core temperature rises, it makes your body want to cool down so you sweat more to lose heat through your skin.

‘Thermogenic’ foods like spices and chilli peppers also increase body temperature as they kickstart our metabolism. This promotes sweating, which is the body’s most effective cooling mechanism.

Are there foods we should avoid?

Foods that require more effort to digest, like those high in protein (meat, fish and dairy), sugar and fibre are thought to generate more body heat. One way of mitigating this is to use citrus-rich marinades on meat to break down the protein structure and soak grains to help make their fibre more digestible.

Try our tasty overnight oat recipes:

Tropical overnight oats
Peanut butter overnight oats

What happens to our appetite when we’re hot?

If you don’t feel like eating as much in the summer, you’re not alone. Seasonal changes including temperature and the number of daylight hours are thought to influence our appetite. One reason for this is that the body tries to regulate our body temperature by cutting down on heat-generating functions like digestion.

While this kind of drop in appetite might be out of our control, we can help ourselves by ensuring the food we do eat is packed with the right nutrients.

See our quick and healthy recipes for nutritious meals you can make in minutes.

How to rest in a heatwave

How can we stay cool at night?

Our guide to getting a good night’s sleep gives some general advice on food choices, but when the weather is hot, thirst is more likely to keep us awake. Many people stop drinking fluids in the evening because they don’t want to be disturbed by bathroom breaks during the night but being dehydrated will also cause you to wake, so make sure you are not thirsty at night and keep a glass of water by the bed.

A hot water bottle filled with icy water will cool bed linen and might help keep temperatures down too.

Get more practical tips from our expert guide on keeping your cool at night.

Should temperatures become excessive, it is recommended that you try to stay out of the heat and cool yourself down as much as you can. Try to be mindful of friends, family and neighbours who might be more vulnerable in these conditions and seek medical advice should you begin to feel unwell.

How do you handle heatwaves? We’d like to hear how it changes the way you eat and hydrate...

This article was reviewed on 11 June 2024 by Kerry Torrens.

A qualified nutritionist (MBANT), Kerry Torrens is a contributing author to a number of nutritional and cookery publications including Good Food magazine. Kerry is a member of the The Royal Society of Medicine, Complementary and Natural Healthcare Council (CNHC), British Association for Applied Nutrition and Nutritional Therapy (BANT).

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