Being hydrated is a fairly simple feat, right? Yet dehydration is so common and we often don’t realise we have it. When was the last time you felt thirsty? You were most likely dehydrated. We are surrounded by water and it falls from the sky, so why do we struggle to provide our bodies with enough of it?
Lets go through some reasons for the lack of cloud juice in our systems.
Reason 1: We don’t know we are doing it
Water is an essential nutrient that makes up a whopping 50-80% of the body depending on age and proportion of fat and muscle. H2O has a number of very important roles in the bodyWhitney E, Rolfes S, Crowe T, Cameron-Smith D, Walsh A. Understanding Nutrition: Australian & New Zealand edition. 2nd ed. Melbourne: Cengage Learning Australia; 2014. including, but not limited to:
- maintaining blood volume and carrying nutrients and waste products in the body
- maintaining the structure of proteins and other large molecules and allowing small molecules to dissolve and react with each other
- involvement in metabolic reactions (AKA ‘metabolism’)
- cushioning and lubrication of the joints, eyes, spinal cord and foetus in pregnancy
- regulation of body temperature
Thirst drives the body to drink, but the thirst response lags behind the body’s needs; in fact, the body is already 2% dehydrated by the time the thirst response kicks in.Whitney E, Rolfes S, Crowe T, Cameron-Smith D, Walsh A. Understanding Nutrition: Australian & New Zealand edition. 2nd ed. Melbourne: Cengage Learning Australia; 2014.
How does thirst work, you may ask? There is a complex pathway involving the neurological and endocrine (hormone) systems of the body. Put simply, the brain recognises a reduced blood volume and a higher blood concentration and it stimulates the feeling of thirst, which drives a change in behaviour to drink fluids. Elderly people have a reduced thirst response, creating an even bigger risk of dehydration and its consequences.
Being dehydrated is a whole lot more than feeling thirsty, though! Here are some of the consequences of dehydration:
- fatigue, low energy levels, tiredness, easy ‘fatiguability’ (a new word for me too, who knew!)
- impatience, lack of enthusiasm, difficulty concentrating, irritability (sound familiar? I’m thinking mid-afternoon at work or uni)
- dry mouth, loss of appetite (mild thirst can sometimes be confused with hunger, discussed below!)
- dizziness, low blood pressure, headache
- reduced urine volume or frequency
- muscle cramps, reduced physical performance, loss of balance, increased respiratory rate
- reduced skin turgor (dry or wrinkled skin)
- high serum creatinine and blood urea nitrogen levels
- high or low blood sodium and/or potassium
- metabolic acidosis or alkalosis
Severe dehydration can lead to confusion, lethargy and pain in the abdomen or chest. The cause of dehydration (medically termed hypovolemia) may involve vomiting, diarrhoea, severe skin burns, polyuria, or pain.
Reason 2. We don’t know how much to have
“Drink more water”, “Drink plenty of water”, “Drink 8 glasses a day” …uh sorry, but how big is a glass? What is plenty? Probably something about “moderation“? Contrary to popular belief, nutrition science is not black and white (sorry!). There is no “right” amount of water everyone should drink each day. The Australian Dietary Guidelines and the Australian Guide To Healthy Eating suggest to “drink plenty of water”, which is suitably vague considering there are so many factors influencing the appropriate amount of fluid intake. The foods we eat help to bump up our fluid intake – it’s not just that stuff from the tap that helps out! Fruit and vegetables are up to 90% water and meats and cheeses can be half water.Whitney E, Rolfes S, Crowe T, Cameron-Smith D, Walsh A. Understanding Nutrition: Australian & New Zealand edition. 2nd ed. Melbourne: Cengage Learning Australia; 2014. Just to confuse things a little more, about 200-300mL of water is generated in the body during the processes of metabolismWhitney E, Rolfes S, Crowe T, Cameron-Smith D, Walsh A. Understanding Nutrition: Australian & New Zealand edition. 2nd ed. Melbourne: Cengage Learning Australia; 2014. …whaaaaat.
The Recommended Dietary Intake (RDI) for water cannot be determined, so an Adequate Intake (AI) measure has been estimated from the observed average intake in the Australian population. The AI’s for water – the daily amounts that appear sufficient for most people in each age and gender group – are outlined here; I won’t go through them all, but I will say that the adequate fluid intake is 3.4L for men and 2.8L for women over 18 years, which includes fluid from foods.
The National Institute for Health and Care Excellence (NICE) recommends 30-35ml fluid per kilogram adjusted body weight each day for people who are not severely ill or injured. So for a 70kg person, this means 2.1-2.45L fluid/day.
Reason 3. We are losing more than we think
Water loss from skin and lungs accounts for 50% of total fluid loss, which is typically between 1.4-2.8 litres (minimum 0.5L/day).Whitney E, Rolfes S, Crowe T, Cameron-Smith D, Walsh A. Understanding Nutrition: Australian & New Zealand edition. 2nd ed. Melbourne: Cengage Learning Australia; 2014. . Sweat is amazing at keeping us cool, but not amazing at keeping us hydrated! Sweat rate is influenced by gender, body size, fitness level, exercise intensity and environmental conditions such as sun, wind, humidity, temperature and acclimation status. To give you an idea, a female running in 19-24˚C at 12km/hr will lose about 1.5 litres of fluid per hour (1.8L for a male) – more than you thought? Yep, me too. We lose about 350mL of water everyday just from breathing! The other 50% of fluid loss comes from faeces (about 150mL) and urine (500-1400mL).
Reason 4. We forget to drink
Have you ever munched on a bit of everything in the fridge and cupboard, then had a glass of water and realised you weren’t hungry in the first place? Our brain can mix hunger and thirst responses up, although there is some evidence to say that thirst may be more motivating to drink than hunger is to eat. Other factors influencing the thirst response are cold temperatures and hormonal fluctuations. Apparently girls demonstrate more favourable drinking habits than boys! Only a few decades ago, fluids were only consumed with meals. Now we eat without drinking, and drink energy dense drinks without need, blurring the relationship between thirst, hunger, eating and drinking.
Reason 5. We don’t like to drink water
You can lead a horse to water, but you can’t make him drink. What if the water is too boring, too warm, too cold, too expensive, too chlorinated, too fluoridated, too plain, too wet?! If it means you’re more likely to meet your daily fluid requirements, buy a filter jug or bottle and keep water in the fridge. Drink warm water with lemon or ginger or herbal tea. Put some fruit in your water bottle. Have soup! There are one hundred and one ways to improve your fluid intake. Although most drinks count as ‘fluid’, the Australian Dietary Guidelines recommend to “limit drinks containing added sugars such as sugar-sweetened soft drinks and cordials, fruit drinks, vitamin waters, energy and sports drinks”. Also the Alcohol Guidelines suggest drinking no more than two standard drinks on any day to reduce the lifetime risk of harm from alcohol-related disease or injury.
It may not be drinking the water you’re worried about but rather the inconvenience of finding a bathroom, poor mobility, incontinence or an inability to swallow. The latter three are best discussed with your doctor. As for finding a bathroom, if you know you won’t be able to drink for a period of time, have an extra glass of water later when you can.
Reason 6. We don’t have access
In Australia we are lucky enough to have generally good access to safe drinking water. Worldwide though, 663 million people rely on surface water from lakes, rivers, dams, unprotected dug wells or springs for their drinking, cooking, and personal hygiene. The good news is the World Health Organization reports the goals for increasing sustainable access to safe drinking water have been met 5 years earlier than planned. Lets drink to that!
Tips for ditching dehydration
- Australians buy 600 million litres of bottled water a year – don’t get me started on plastic waste. Get a drink bottle you like and carry it with you. You won’t have to buy drinks and you’ll be tempted to lighten the load in your bag! (Seriously, get a bottle that you like, if it leaks you will be frustrated and we don’t want that).
- Set yourself goals. Have a water jug at home or at your desk, or count how many drink bottles you get through in a day.
- Have a glass when you first wake up in the morning. If you’re a sipper, sip more often. Set a reminder on your phone.
- Don’t like water at room temperature? Chill it! Or get a metal drink bottle to keep it cooler. Don’t like it cold? Have a warm cuppa instead. Hydrating isn’t the same for everyone.
- Drink water from a wine glass or fill your stubby with water between beers.
- Check out the Sports Dietitians Australia and the Australian Sports Commission websites. Calculate your sweat rate and drink 125-150% of fluid lost over the 4-6 hours after exercising.
- Have a look at the Nutrient Reference Values for water, especially if you’re pregnant, breastfeeding or have children as the requirements are different for these groups.
- See the European Hydration Institute for information sheets and tips for staying hydrated in different situations.
- The most efficient way to check if you’re getting enough fluid is the colour of your urine. It’s only human! The optimal colour is pale straw or transparent yellow. If the urine is dark yellow you’ll need to drink water soon.
Please don’t go and drink 20 litres after reading this article. There is such a thing as overhydration or water intoxicationWhitney E, Rolfes S, Crowe T, Cameron-Smith D, Walsh A. Understanding Nutrition: Australian & New Zealand edition. 2nd ed. Melbourne: Cengage Learning Australia; 2014. and it’s not pretty. Drinking too much water can lead to shifts in electrolytes in the blood and body cells (e.g. hyponatremia), potentially leading to brain swelling or death. People with kidney disorders (reduced urine production) are at risk of water intoxication and may need to restrict fluid intake. Athletes also have to be aware not to drink excessive amounts of fluid. It is always a good idea to see a doctor and/or Accredited Practising Dietitian to make sure you are drinking the optimal amount of fluid for your body.
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