Hydration

There is one hell of a lot of stuff written about how much to drink and when to drink it and why you should do so. Not much of it seems to have much relavence to individuals and their individual needs. Most of it is incredibly simplistic. For instance the "8 cups a day" rule that everyone must drink at least 8 cups of plain water (excluding Tea and Coffee) if followed would mean some people drinking far too much water and some people drinking not enough.

Following such a rule blindly means choosing to ignore what your body already knows.

Before talking about hydration I think it is sensible to talk about basic biology to help you make informed choices.

Biology 101 - History

The current fetish in the west seems to be to drink [mineral] water almost continually and to spend only slightly less time urinating it back out again. The assumption seems to be that the human body can go at most 10-15 minutes without water.

I want to examine this by taking you back through the mists of time, to before bottled water was invented...

Early in the inventions of man amongst fire, spears and clothes were water carriers made out of animal bladders. Before that time the human race had existed (how long depends on your beliefs). Clearly water carriers were not invented because of a marketing campaign but to meet some basic need. That need must have been to allow us to increase the distance we could walk between water sources.

Carrying water is and always will result in carrying something heavy. There is no point in doing that unless the benefits outweigh the extra energy expended. Clearly they did.

Before the invention of the water carrier is it sensible to believe that we were forced to live near a continual water source in order to satisfy our need for continual drinks of water? Clearly this cannot be so since it is quite clear that we have been hunter-gathers for a very long time and the one thing that we know about animals is they move - especially the really big meaty ones. Obviously then we must also have moved and stalked the animals. This must have involved moving away from water sources and perhaps going without water for some time.

With all this as background the first thing that I want to suggest is that there is no need to drink water continually and that it is quite OK to have gaps where you do not drink something for quite some time - if necessary.

The fact that we do not do so is merely because we live and are used to an environment where water is freely available even though that is only a recent thing.

If we used to move between water sources (just like we do in backpacking) it should be clear that the body is quite capable of doing this - within limits. Those limits are a lot more generous than we are led to believe - up to 24 hours.

The problem is that most of us are used to drinking water as and when we want it and are not used to going without water for any length of time. There are a few exceptions. The armed forces do still train people to have periods of lower water intake. The rest of us tend not to be trained in such a way.

Lack of water in the long term will cause health issues - such as death. However, in the short term mild dehydration (having less water than optimal) has no significant side effects and repeated exposure to them (i.e. training) will reduce them.

Biology 101 - Water Loss

Clearly if we need to keep taking on water from time to time we must be losing it from somewhere and we must have lost it for some reason. Let's examine a few of those.

Biology 101 - Water Loss - Biological Processes

In the same way that we 'burn' food we also burn water so even doing nothing means consuming a little water.

The other thing that we do with water is use it to store things. All the cells in the human body tend to have a quite narrow set of 'happy values' for the concentration of chemicals within them. Likewise our blood is happiest at certain densities. If cells fall outside of these 'happy values' they stop working effectively.

Anyone who does endurance training will be familiar with the bloat caused by carbohydrate loading. Endurance atheletes have developed bodies that are capable of storing larger than average amounts of glucose. Unfortunately this glucose can only be stored as a solution and that means lots of water. This leads to being 'bloated'.

What then happens is that as an athelete exercises those stores of glucose are used up. As this happens water is 'released' and then has to be dealt with. When this happens urine output will typically increase and the desire for water will decrease.

Biology 101 - Water Loss - Breathing

Every breath contains water. Over a day this adds up. If you weigh yourself at night on a pair of digital scales and again first thing in the morning you will notice a change in weight. That change will vary but will be a few hundred grams.

The chances also are that when you wake up you will have a full bladder and a desire to urinate. Where did all this water come from? The simple answer is that you have been using some of your glucose reserves through the night and in order to maintain balance releasing the glucose for burning has also released the water that it was stored in and now that water has to go somewhere out of the way...

Biology 101 - Water Loss - Sweating

Your body only sweats for one reason - to lose heat. Your body has a quite narrow range of temperatures in which it prefers to operate and if you move outside of those temperatures it will either shiver or sweat to restore balance.

Exercise produces heat and so may result in sweating. A lot of sweating that people do is unncessary and only occurs becasue they are wearing too many clothes.

Even if it is only a few degrees above zero, if you are exercising heavily (such as climbing a steep hill) then a thin top may be all that you need to keep warm.

You can do a lot to minimise sweating by getting used to your skin feeling a little cool.

When it is safe to do so it is worthwhile to get used to wearing few clothes than you think are necessary whilst exercising outdoors until you get used to a skin that feels cooler. It is just simple adaptation and could help you to carry less water and feel more comfortable.

If your body is unable to sweat (due to lack of usable water in the body) then it will be a problem and a serious one. It is much more sensible to learn how to minimise sweating by dressing more sensibly for the conditions. If you are sweating in the depths of winter then something is not quite right!!!

Biology 101 - Water Loss - Urination

In the west Urine has now reached almost sacred status and people are obsessed with how much of it there is and what colour it is.

Let's take a reality check here and talk about why we need to urinate. It's not a fashion statement!!!

The first and most obvious reason why we urinate is to get rid of water soluble toxins from our body - many of which are natural byproducts of being alive. Anyone who has urinated (which is everyone) will be quite familiar with sunflower yellow streams of urine and clear water streams. The only significant difference betwen the two is the amount of water.

So, the second reason we urinate (which is not often talked about) is to get rid of excess water. That's right excess water. If you drink more water than your body needs it has a problem. It has very few places to store excess water unless their is also an excess of something else such as sodium or glucose. We are not camels!!! Instead what happens is that the excess water is pushed through the kidneys and into the bladder. By doing this the body maintains a healthy electrolytic balance elsewhere.

Everyone is told to drink more water and then they urinate more often and with greater volumes. Can you see there might be a connection?

Like everything else in your body your kidneys have a range at which they perform best - but that range is quite wide.

Water is treated as a valuable resource and the bladder is treated as an internal water bottle that can be filled or emptied of water by the body in order to keep the body in good working order.

If your kidneys are processing lots of water they are doing more work than they need to. Likewise if there is insufficient water the kidneys have to work equally hard to keep some quite strong solutions of urine safe.

There are no magic numbers as to how often or how much urine should be produced. It depends on you.

Biology 101 - Over-hydration

This is fortunately quite rare.

If your body absorbs too much water and cannot expel it (either via sweat or urine) then it will stop working and you die. Which is bad mmmkkayyy! In recent years the only time this seems to happen (outside of illness) is when illegal drugs are involved. It is documented that several people have died through taking Ecstasy and the reason has been that they had an artificial thirst which resulted in them drinking lots of water in excess of what the body could cope with.

If you try and forcibly over-hydrate yourself the result is just lots of urine.

Biology 101 - Dehydration

This is one term that is over-used and abused - mainly by people selling processed water. Dehydration is simply when your body has less water than is optimal. It can vary from mild to severe to fatal.

The problem with much that is said about Dehydration is that it does not take into account normal variances in the amount of water in the body.

If you have not eaten for a few hours or more the amount of water in your body naturally falls (and is sent to the bladder) as glucose is used up. You are still in perfect health and fully hydrated even though you had less water than before in your body. This is not dehydration - this is normal!!!

Likewise if you eat a large meal after not having eaten then all that extra food is processed and a large chunk of it will be stored as glucose. In order to do this you will feel thirsty and drink more water. This water is then used to store the glucose in solution.

For most people the rough figure is that glucose stores in the body will be equivalent to 2,500 calories. If you have done endurance training over many years that figure will be higher.

Having done lots of endurance training myself I know that the variability in water for me is about 2Kg in weight which is basically 2L. So, depending on my levels of glucose reserves my weight can vary by 2Kg and I can still be fully hydrated.

Likewise, if I am exercising in a way that depletes those glucose reserves I can lose 2L of water from my body via sweat, breath or urination (or a mixture) and still be fully hydrated and in good health. Now 2Kg is over 2% of my bodymass which is the suggested point at which dehydration can occur. That is simplistic.

Now, what would happen if I am not burning glucose (because it is all gone say) and I am sweating heavily or that the water released by burning glucose is less than the water required for sweating. Over time I will dehydrate.

Very simply my body will move from being 'happy' about the amount of water to 'unhappy'. An 'unhappy' body will protect itself.

So, the first thing that happens is you start to have a dry mouth and feel a little thirsty. If that is ignored then you will slow down - maybe by as much as 25% to burn energy less quickly you will also feel a little tired. You will then start to become lethargic, light-headed and lose the ability to think straight. The longer you leave it the worse it becomes until you die.

Before science was invented the human race existed and managed to drink enough water. How was that possible?

Biology 101 - Diuretics

Coffee, Tea and Alcohol are the official bad boys. Unfortunately their badness is overstated.

If I drink a pint of beer then following that drink will come the natural desire to urinate. The same would be true if I drank a pint of water.

Likewise if I drink 6 cups of coffee a day then I will urinate more than if I drank 3 cups of coffee a day. However, if I drink 3 cups of coffee a day and 3 cups of water a day the difference between that and 6 cups of coffee is not that great.

These days I drink half-caf coffee and intersperse that with decaf coffee. I have no idea if it has made any difference to my hydration levels.

In the UK the Government in their infinite wisdom have sometimes suggested that the '8 cups of water a day' should be in addition to any tea or coffee. Every time I have tried to follow that advice the result has been quite predictable day in and day out - more urination. What was the point?

I think for most people the diuretic effects of tea or coffee are ofset by the amount of water contained in the tea/coffee and in the food that they eat. It wouldn't hurt to drink more ordinary water and less coffee but it's not essential.

When at home or in the office the reality is that most of my water is in the form of some sort of flavoured drink - such as coffee or decaf or fruit juice and not plain water.

Hydration - How Much?

So far I have made it clear that the body needs water and that either too much or too little of it is a bad thing. I have also made it clear that I think that official guidelines are a bit of a nonsense.

The first thing that I did when starting this section was to research where this 8-cups idea came from and on what it was based. The best thing that I could find was the Space Programs for both Nasa and Russia. Here it was objectively stated that Astronauts needed anything between 2.2L and 2.7L of water a day in total. This was also based on some of that water being used to rehydrate food.

So, from NASA we can see that an Astronaut who is very physically fit and healthy working and exercising daily in a temperature-controlled environment needs at least 2L of water a day which includes water in food.

So, the first thing to ask is "How wet is your food?" Pasta in sauce is much wetter than Tacos. Soup is even wetter still. The point is that the body only recognises water it does not recognise where it comes from. Water in soup is no different to plain water and is absorbed just as well.

If you are sat slumped in a chair your water requirements will be a lot less than if you are running a marathon. How can you tell how much extra water that you need?

My own backpack tells me that in the winter I will use very little water on a hike and in the summer I will use a lot more. I know this by the simple fact that if I take 3L of water out on a day hike in winter it is likely that 2L of that water comes back home with me. Likewise in the summer very little of that 3L of water will come home with me.

Hydration - How Often?

If you drink water too frequently that is just as dangerous as drinking water too infrequently. Initially the worst thing that can happen is that peak performance will drop compared with what it could have been.

When I was younger I used to do a lot of long distance endurance cycling. Naturally, I was obsessed with food and water.

At the time I was doing this the 'offical' wisdom was to drink one pint of water per hour. Whenver I did this I spent as much time urinating as I did drinking. It seemed pointless.

When hiking and backpacking I have found that if I use a bladder such as camelbak that yes I do in fact consume more water. I also urinate more. I think the two might be connected.

Hydration - How Much for you?

After trying all sorts of things and following all sorts of 'official' and 'scientific' advice I have found that the simplest thing to do is to follow a very simple and very old Zen proverb "When thirsty, drink. When hungry, eat. When tired, sleep".

I have found that just drinking when thirsty (or more accurately when I feel like a drink) is sufficient to keep me fully hydrated during a day. If I do not drink as often as I want to (say to ration water) then I will start to obsess about water. This is a sure sign that I am not drinking enough.

Once you have started to listen to your own body rather than some scientist then hydration will not be an issue - ever. Thirst and the gentle nudge of a dry mouth or thoughts about water will guide you to have a drink. If one drink is not enough you will feel the need for another. After a few gulps of water you will know if that is enough or more is required.

If I am at a rest stop what I can do is have a drink of water and sit for a few minutes. If I still feel the need for whater I can have another drink. Sometimes one sip will be enough. At other times I might drink 0.5L.

Hydration - How Often for you?

Again, this is just simply a case of learning to recognise when your body wants water.

I have completely given up any fixed pattern of drinking water either at home or in the wilderness. I find it much simpler to drink when I am thirsty and for as long as I feel the need to drink.

In practice this means that on most days when at home or in the office I will drink around 2L of water (including Coffee, Halfcaf and Decaf) but that it might well be that any particular cup of coffee is only half drunk. Sometimes at breakfast I might have one hot drink, sometimes two.

Overal, even though my average might hit 'official' figures for water consumption on some days it will be less and others a lot more - based on what I am doing. The point is that I drink according to my actual needs and not some external ideal.

Hydration - What to drink?

There are a large number of sports drinks on the market. Most are nothing more than expensive sugar drinks. Some are 'isotonic' which means that along with the sugar are included some essential salts that are lost during sweat. More worrying is the fact that some of these drinks include strong stimulants that can be unhelpful.

If you are drinking these drinks in volume - such as all day then you will need to be very careful to find a drink that works for you. Some of the drinks may be too rich or too weak for your stomach or personal needs and can lead to discomfort. Many drinks are available in powder form and can be mixed en route.

In the short term some of these drinks do make a difference and do help to replace both essential fluids and essential salts. If you try and use them for extended periods or on multi-day trips you may find your body rebels a little and that you rapidly lose the desire to drink these things.

For extended trips there is the issue of keeping your drinks bottles sterile. Most sports drinks will leave behind a very friendly environment for all sorts of bacteria and nasties.

Overall then, for a single day's hydration these drinks can perform a useful purpose. On the first day of any trip I do tend to carry 0.5 to 1L of my personal favourite sports drink that works best with my bdy. I then throw the bottle away at a suitable point.

On longer journeys I tend to stick with water - not because it is 'best' but because I don't have to worry about cleaning the bottles. I then make a point of increasing the salt intake in my diet to compesate for the loss of salt through sweat.

Hydration - Bladder or Bottle?

Many years ago when I was doing lots of endurance cycling I used to work on a two-bottle system on the bike. I would have two 0.75L bottles one of which would be the active bottle and one a 'reserve'. Once I started drinking from the 'reserve' bottle I would consider looking for a new water source to replenish the other bottle.

I have experimented whilst hiking with both bladders and bottles. Of the bladders I like the Camelbak for being relatively taste neutral and having a good bite valve. The issue I have with the bladders is that I am never sure how much fluid I have left - and that is a very important thing to know. The Camelbak is however relatively heavy when compared with the equivalent Platypus bottle(s).

In general then I now run a two or three bottle system with my backpack in a similar way to when I did on the bike. I have two bottles in mesh pouches on the pack which are my day bottles. I have a third bottle in the pack which is my reserve or night bottle.

In this way I can carry up to 3L of water (unless I need more) and be sure of how much water I am carrying at any time.

The only problem with this bottle system is that weight tends to be low on the pack whereas with the bladder the weight does at least start evenly distributed over the pack.

Ultimately the 'best' system is the one that works for you and ensures that you stay hydrated and know how much water you have.

Incidentally my water bottles are either Platypus or Source bottles. Both have proved to be very tough and light. Many people use disposable plastic drinks bottles and this is also a great way to find a cheap bottle with a sports cap.