Do I really need 6 to 8 glasses of water a day? Or is it 2 litres? Can you really ‘drown’ if you drink too much? Do I have to drink only plain water? How will I know when I’m dehydrated?
We can survive for weeks without food (not that I’d recommend it) but we’d die within a few days without water or at least something that provides us with water in one form or another. Our bodies are on average 60% water, after all. Our blood, cells and muscles contain water aplenty and it’s needed to regulate our body temperature, lubricate our joints and allow most of our metabolic reactions to occur. But there are so many myths about how much and what type of fluid we need. Here’s the lowdown on H2O.
How much water do we actually need?
There is very little scientific basis for the 2 litres or 6 to 8 glasses rule we’ve all grown up with. That’s not to say hydration isn’t important – it massively is – it’s just that what we need depends on so many variable factors that there is no one size fits all rule. Clearly, the larger our body, the more water we need but there are so many other influences on our hydration status and these can change from person to person and day to day.
Clearly, on a hot and dry day, we’ll lose more water in sweat than on a cold rainy day, hence why we need more water in the summer. If we do physical activity, we lose water as sweat, to cool us down, and in the water vapour we breathe out, so, again, we need more water than when we’re sitting on the sofa watching Game of Thrones. Add to this the fact that we all have a different sweat rate. My mum claims to never sweat whereas I can start exercising and I’m ‘glowing’ within minutes and I’m miles fitter than my mum!
The NHS still recommends 6-8 glasses or 1.2 litres of water a day, on top of foods that themselves provide fluids, to avoid dehydration. It’s not wrong as such but your individual needs may vary. Most people probably don’t need less but some people might need more.
How do we become dehydrated?
Obviously we take in water in the drinks and foods that we consume (more on this later) and we produce small amounts in the body as a result of metabolic reactions but we lose water in more ways than you may imagine. The primary loss of water from the body is from pee and sweat but we also lose water in our poo and in our exhaled breath – you can see the latter when you breathe out onto a glass mirror or into cold air in winter. Failing to take in enough fluid coupled with losing a lot through sweat is a fast track to dehydration
How do I avoid dehydration?
2 ways. Drink when you are thirsty. There’s no truth in the urban myth that if you are thirsty, you’re already dehydrated (unless you’ve ignored your thirst for ages). Thirst is there for a reason – to encourage you to drink to avoid dehydration!
Check the colour of your pee. Yes, I know it’s a bit gross, but if it’s dark (like an amber or honey colour) and smelly, you’re probably dehydrated and could do with getting some fluid. If it’s pale and straw coloured, you’re probably well hydrated. You can find a good chart here with plenty of other advice on hydration.
Bear in mind though, if you’re taking certain vitamins or have some health conditions, the colour of your pee might be different (for example, I have Gilbert’s syndrome, which is a liver condition in which I sometimes have high levels of bile salts in my blood and that can change the colour of my pee). Also, always remember when you’ve eaten beetroot, or your pee and poo could have you running for the doctor! And seriously, if you do have blood in your pee or poo, please go straight to the GP.
What happens when I’m dehydrated?
A loss of just 2% body weight from lost water can result in headaches and tiredness which can affect your ability to concentrate or exercise. Prolonged dehydration can increase the risk of urinary stones and even cancer of the urinary tract and bowel. Loss of 15-20% of body weight as water can be fatal and can ensue in as little as 2 or 3d if you don’t drink or eat anything that provides fluid.
Remember though, you can drink too much too! There have been a few cases where people (often marathon runners but also people who’ve taken the advice to drink more water to an extreme) drink large amounts of water in a short space of time and cause a dilution of sodium in the body, known as hyponatraemia or water intoxication. This can lead to lung congestion, brain swelling, seizures and even coma. If you’ve been drinking lots and lots, particularly while running, and you feel lethargic, confused or nauseous, maybe stop and consider how much water you’ve been drinking. Call NHS 111 for advice if you are concerned.
Do I have to drink only water? It’s so boring!
Water comes from many drinks and from a lot of the foods we eat too. Most fluids count and can hydrate us but water is often seen as the best option as it’s calorie free, doesn’t cost anything and is pH neutral so won’t damage teeth like sugary drinks or acidic drinks like fruit juice or colas (even the sugar free versions of cola are acidic).
Tea and coffee also count but remember they can stain your teeth! The amount of caffeine present in high volume drinks is unlikely to cause dehydration via its diuretic effect ( though maybe steer clear of back to back espressos) so this really isn’t a concern if you drink a few cups a day, but try to mix up tea or coffee with water and other caffeine free drinks. I just get concerned when people avoid tea and coffee entirely because they think they are dehydrating when actually, particularly for older people in care homes, they can be a very valuable source of hydration that, when removed, is not always replaced with a palatable alternative, leading to dehydration.
Milk has a high water content and delivers useful nutrients too. It’s actually a brilliant sports drink and can help to rehydrate and replenish after training without the need for sugary, brightly coloured alternatives. It’s great for kids after they’ve been active. Obviously though, it’s not calorie-free, so if you’re watching your weight, it might be better to stick to water. The area of sports hydration and performance needs a blog of its own but suffice to say, if you’re exercising for less than an hour, plain water is fine for hydration.
Even beer, with its high water to alcohol content can be hydrating but again, there are probably better alternatives! Wine and drinks with higher alcohol content tend to be more dehydrating so again, I wouldn’t rely on alcoholic drinks to boost hydration! If you’re drinking alcohol, make sure you have some water alongside it to ease your woes the next morning.
If water is just too boring, then you can add a little flavour by infusing it with lemon or orange peel, cucumber, mint or berries. Avoid using too much lemon juice as this can make the water too acidic and damage teeth. Sugar-free cordials are fine but some people have concerns about the use of artificial sweeteners. These are deemed to be safe by the European Food Safety Authority but recent research has questioned the effects of artificial sweeteners on our gut bacteria. This is very much a watch this space situation but small amounts of cordial to pep up water is fine.
The NHS has lots of information on drinks and hydration too.
What we often forget is that many of the foods we eat are rich in water. Fruit and vegetables can be up to 95% water (leafy greens, broccoli, carrots, berries, apples, pears, for example) but most fruit and veg are a good source of water as well as fibre, vitamins and minerals. Yoghurt, fish, seafood, eggs and even pasta are also pretty watery, so we do get a lot of the fluids we need from the food we eat.
This is particularly useful if you have kids that don’t really like drinking water. Make sure they have plenty of fruit and veg (an uphill struggle I know but check out my blog on getting kids to eat veg) to keep their fluid levels topped up, especially in summer. Try making fun infused water with them too to get them interested.
So there it is. Hydration is vitally important but it is really hard to say how much an individual needs. My advice would be – drink when thirsty and check your pee colour. And maybe don’t rely entirely on Sauvignon Blanc to meet your fluid needs. Sorry about that.