Updated: Mar 25
Being dehydrated can affect your workouts and athletic performance; just losing 2% of your body weight in fluids can decrease performance by up to 25%
Are you drinking enough water each day? Let's explore ...
How much water do we need to drink?
We cannot live without water. For men water makes up roughly 60% of our body weight and for women 50-55%: womens is slightly lower due to a higher body fat percentage(1).
Do you drink enough water each day? The recommendations for how much water we should drink are 6-8 glasses of fluids per day approximately 1.2 litres. This recommended fluid intake per day can include water, tea, coffee, milk and low sugar or sugar free drinks(2) and foods account for roughly 20%(1).
Eating food may stimulate drinking; research has shown that 75% of our fluid intake occurs when we eat. Eating water rich foods have been proven to be beneficial for helping to keep hydrated. The amount of water in food varies: fruits and vegetables can contain over 80% water, bread and biscuits less than 40% and savoury snacks and confectionary 10%(7). Research has also been shown that when people have water alongside a meal it promotes satiety (feelings of being full)(10).
It is important to note that how much we drink can vary depending on numerous factors: diet, physical activity and the environment(5). We need to replenish our fluid levels regularly to avoid dehydration as we lose water from the body through different forms including urine, sweat and from our breath(1).
Why do we need to drink water?
We need to drink water for numerous roles within the body including regulating our temperature, transporting nutrients around the body and removing waste products from the body(1). We need to keep ourselves hydrated to provide adequate hydration and electrolyte homeostasis; drinking enough water to stay hydrated is vital to maintain our health and the function of our body(8).
What happens when we are dehydrated?
Research has shown that being dehydrated by just 1% can affect our mental and physical functions. Common mild symptoms of being dehydrated include dry mouth, headaches and poor concentration(1) - have you ever experienced one or all of these? As the levels of dehydration increase it has been found that we decrease in our brain function and even our moods can be affected(4). Symptoms of more serious dehydration can include urinary tract infections and the development of kidney stones(3).
The level of water in our bodies changes with our age; newborn babies have a higher body fluid level than adults and the eldery have a lower body fluid(3). Population groups who are at higher risk of dehydration include athletes, babies and infants, older people, people with alcoholism and diabetes(6).
Does drinking water help to lose weight?
Research shows that having a higher body fat percentage leads to a lower body fluid percentage(7). Drinking water increases the amount of calories that you can burn(12). Studies have shown that overweight people who drank 1-1.5 litres of water daily for a few weeks significantly reduced their weight, BMI, waist circumference and body fat percentage. One study in particular examining a group of overweight women found that over a 12 month period increasing their daily water intake to over 1 litre resulted in an extra 4lbs of weight loss(12).
Drinking water and exercise?
Being dehydrated can affect your workouts and athletic performance; just losing 2% of your body weight in fluids can decrease performance by up to 25%. Starting a workout dehydrated can make you feel dizzy, lethargic and lead to muscle cramps sooner(13).
If you are physically active sweating is the highest variable for losing water(9) and losing water through your breathing rate being increased(13). Water helps your body to exercise efficiently; water lubricates your body and helps many chemical reactions in the body and being dehydrated can slow down the recovery of your tissues and muscles(13). The amount of sweat you lose through exercise depends on the intensity of the exercise, your individual sweat rate, what clothes you wear and what the temperature or humidity is when exercising(9).
A study examining seasoned runners participating in a 10-mile race shows that runners were only replacing their fluids lost through sweat by 30%; the runners were underestimating their sweat losses by an average of 46% and their fluid intakes by 15% (13).
How much water do I need to drink when exercising?
Firstly ensure you are meeting the daily recommendations for fluid intake of 1.2 litres(2) to ensure you are hydrated before starting your exercise session. A suggested formula for fluid intake and exercise is below, but note you may need to drink more if you excessively sweat, the temperatures are higher or you are training indoors(13):
1-2 hour before your workout drink 0.43 - 0.57L (15-20 fl.oz)
15 minutes before your workouts begins drink 0.23-0.28L (8-10 fl.oz)
During your workout drink X every 15 minutes 0.23L (8 fl.oz)
How to monitor hydration?
Your hydration status can be measured through changes in your body weight(5). An easy marker for monitoring your hydration status can be looking at the colour of your urine(4). The chart below shows changes your urine colour may vary with hydration status(14).
Can you drink too much water?
It is possible to drink too much water, however it is difficult to do so, but can be found in endurance athletes but you would have to drink gallons of water(13). Over-hydration can cause an impairment in the body being able to get rid of excess water(1).
Article Written by Jade Mottley – Fitness Coach & Nutritionist