The last time my fellow Scot Billy Connolly was in Sydney I went to one of his gigs. He had me in stitches over his comments on drinking water. He said “when I was a kid you had a glass of water before you left the house. Now people walk about with huge bottles of water as if they’re going to be in the desert for the day”. It struck a chord with me as I see people at two ends of the extreme. There are those who are certainly not drinking enough, and suffering the symptoms of mild but chronic dehydration, but there are also a growing number of people who are overdrinking. This also stresses the body and can be extremely harmful.
Let’s start with those at the lower end of the scale. Dehydration, by as little as 1% of your body weight, significantly affects your exercise performance and your brain performance. You may feel a dull headache and struggle to concentrate, and you may feel lethargic. The concentrated urine being produced in your kidneys and stored in your bladder make for a wonderful breeding ground for bacteria, so infection is more likely. More severe dehydration will result in a drop in blood volume and your heart will struggle to pump the remaining blood around the body so that you will feel increasingly unwell and would eventually pass out as blood fails to reach your brain in sufficient quantity. Fortunately you will feel thirst well before this happens and so this kind of dangerous dehydration generally only occurs if you are sick. However the chronic mild dehydration can indeed be happening without you being aware that this is the problem. It’s easy to attribute tiredness and headaches to stress or a bad night’s sleep, without thinking about how hydrated you are.
At the other end of the scale I have had clients tell me they drink 3L or more a day religiously. They carry a water bottle at all times and have the idea that “more is always better”. Many believe that drinking more water will help them to lose weight or that it helps them to detox. In fact drinking more water than your body needs just makes your kidneys work harder to eliminate the excess. That just means you’ll run to the loo more often. You can in fact drink yourself to death (although usually this only happens if you are also sweating profusely and losing sodium in your sweat) by taking in so much water that you dilute the amount of sodium in your blood to the extent that your muscles can no longer function properly. This is called hyponatraemia. These cases have happened recently with people walking the Kokoda Track in Papua New Guinea and in long endurance events such as marathons. But even for the rest of us on a daily basis, overdrinking is not helping your health.
So how do you know where you have the perfect balance? There is no optimal amount of water I can give you to drink throughout the day. There are too many factors that affect it. Air conditioning or heating, humidity, your sweat rate, whether or not you have exercised, the water content of the foods you have eaten are all factors that influence how much fluid you need to take on board. The only way to tell if you are hydrated well is to check out the colour of your pee. If you’re running to the loo every half hour and your pee is almost clear you are overhydrating. Conversely if you are only going a couple of times in the day and your pee is darker than a pale straw colour, you are dehydrated. It really is that simple. There are charts you can download to compare the colour and get a measure of how hydrated you are – sports dietitians will use there with their athletes – but for every day life a quick glance will tell you all you need to know. One thing to watch for is if you are taking vitamin/mineral supplements the excess is excreted in your pee and colour it (Berocca yellow does not mean you are dehydrated!). Certain medications may do the same thing.
Remember that it is not just water that counts towards hydrating you. Coffee is not a diuretic as commonly believed. A large amount of caffeine certainly would be, but with a cup of coffee the water and milk (if you have it) result in a net fluid gain. Tea, vegie juices, salad veg, soup, milk on your cereal and so on will all contribute. All that said make water your main drink to quench your thirst. If you are doing a long exercise session of more than 90 mins consider using an electrolyte solution. The additional sodium will help you to absorb the fluid faster and hang on to it to hydrate cells throughout the body. (If you also need additional carbohydrate consider a sports drink).
So I reckon Billy is onto something. There are few places you will be in the day where you can’t get a glass of water. But I do urge you to limit buying plastic bottles of water to when you really need to. We have an enormous problem with plastic bottles in our landfill and a frighteningly small proportion of them actually make it to a recycling plant. We are fortunate in Australia to have safe clean drinking water from our taps. Let’s use it and best of all think of all that money you’ll save.