Are you drinking enough water?

Water, water, everywhere, but how much do we need to avoid dehydration? Dr Adam Carey takes a look

Water is essential for life. While we can go without food for weeks, after only a few days without water we would perish. And even going without it for a relatively short period results in poor performance, especially when it comes to sporting activities in the hot weather.

By the time an athlete is three per cent dehydrated, which can happen before they even feel thirsty, they will have lost 10 per cent of their strength and eight per cent of their speed. Sports experts are now starting to recognise that it is not only physical performance that suffers from dehydration, but also mental performance. The same can be said for non-athletes too. So what should we be doing to make sure we reach our daily quota?

The Basics

We hydrate by drinking but also from the foods we eat. Food provides about a third of the water we consume. Additionally, we generate water from the metabolical processes that burn carbohydrates, protein and fats within our cells. Fluid is lost in urine and faeces, but also when breathing and through the skin, both of which are affected by the climate and physical activity.

Interestingly, drinking relatively small amounts of water seems to satisfy our thirst. This is fine most of the time, but the sweat loss that can occur during exercise may not be adequately replaced if we rely on our thirst response alone. This is why the advice is to drink regularly during exercise.

Monitoring Levels

So just how much fluid do we need each day to stay hydrated? And when do we need more? In the UK where most of the time the temperature is below 20°C if we are active, aiming for a total fluid intake of around three litres a day is a good start. When exercising, sweat rate increases and you should aim for about a quarter of a litre for every 20 minutes of activity.

It is actually quite easy to tell if you are drinking enough. Your urine should be clear and barely change the colour of the water in the toilet. If it is dark then you are dehydrated. The first pass on the day will be dark, as urine production naturally falls during the night. Other things that may affect the colour include the B vitamins, which tend to make urine fluorescent yellow for a while after taking and large amounts of beetroot, which can give it a red tinge.

Thinking Ahead

When you drink is also critical. It is important to drink water before and during things like exercise, studying or working. It is also a good idea to drink around half a litre of water soon after waking before having breakfast. If you have been dehydrated most of the day and then decide to correct this during the evening it will just result in a disturbed night’s sleep and poor function during the day.

Hydrating Choices

I am often asked: “what is the ideal drink?” As a general rule the answer is the main drink of the day should be water. There is nothing wrong with the odd cup of tea or coffee, but too much can affect sleep quality.

  • Rob Hobson, Healthspan Head of Nutrition says; “While caffeine is a mild diuretic, as long as you don’t overdo it, you won’t end up passing more water than you take in. The same cannot be said for most alcoholic beverages. These are actively dehydrating, which is why you feel hung-over after over-indulging.

Rob’s top tip is to try a squeeze of orange or lemon in your glass can add zest to a bland drink of water

If you are considering prolonged bouts of exercise then it is important to consume some electrolytes (salt) with your water, which is where a sports drink is helpful.

Water Quality

The quality of the water you drink is also important. In recent years there has been a massive growth in bottled water sales, but in the UK the tap water is generally safe to drink and considerably cheaper. There may be concerns about its quality, but the other side of the coin is the significant negative impact to the environment in the production, transport and disposal of plastic bottles, most of which end up in land-fill sites.
If you are worried about the quality of your tap water you can buy simple jugs that contain a carbon filter. This can help with any quality concerns while also being kind to the environment.

Hydration in numbers
  • When an athlete is 3% dehydrated they will have lost 10 per cent of their strength and eight per cent of their speed.
  • Food provides about a third of the water we consume
  • Only 9.3% of adults drink the recommended 2 litres of water a day