How Much Water Should You Drink?
As with many areas of nutrition, there is a great deal of information available online when it comes to how much water you should drink. However, who knows what to believe and are there different considerations for different circumstances?
Why is water intake important?
Water is the most abundant component of the human body, comprising approximately 45%–75% of bodyweight depending on age and physiological status (1). It is considered an essential nutrient (2).
Functions of water include:
- Transporting nutrients
- Regulating body temperature
- Being solvent for many organic and inorganic materials
- Lubricating joints and internal organs.
- Providing structure to cells and tissues, among others.
Water is of such great importance that humans could only survive 2 – 4 days without it (1)!
Despite the fact that we are all aware of how important it is to drink enough water, consumption amongst the population shows a high prevalence of inadequate hydration habits (3).
It’s something so simple that can have so many positive health benefits and yet many of us struggle to up our water intake.
What are the consequences of not being hydrated?
Our bodies have smart systems in place to maintain water balance (input vs output), but deficits can occur from inadequate fluid intake (amongst other reasons)(4).
Signs of dehydration can come in many forms; headaches, dizziness, low energy levels and even digestive problems.
Dehydration can affect many different situations:
- At work
Water is used by the body to transport nutrients to all of our cells. When we are dehydrated, our brain functioning is impaired and we can suffer from daytime fatigue.
If you feel like you’re falling asleep at your desk mid-morning, this could be due to a lack of hydration.
During intensive exercise, we lose a % of our body weight through sweating. If the body is not rehydrated throughout and after physical activity, dehydration can severely impair physical performance, having a drastic effect on our strength, endurance and muscle recovery.
One of the primary reasons for this is that dehydration affects our core body temperature and can cause an increased sense of fatigue. If you are trying to build muscle it is vital you are taking in enough water during training sessions.
- Fat loss
Ensuring we are drinking enough water can also be an effective way of stimulating weight loss. Not only does our appetite decrease naturally when we are substantially hydrated, but we often mistake thirst for hunger cravings and can often overeat because of this.
When we are dehydrated our bodies tend to hold onto any available water in our bodies as a survival mechanism, which can cause bloating. When we are drinking enough water, this effect is reversed, and our bodies are encouraged to release more and retain less water, as it is no longer threatened with dehydration.
In addition to tackling the effect of bloating, water is used by the body to maintain a healthy digestive system. The stomach needs water to produce hydrochloric acid used to break down the food we consume effectively, and to ensure a healthy bowel function.
By supporting the healthy functioning of both the liver and the kidneys, water also aids in effective detoxification of the body. The kidneys use water to fuel their ability to filter toxins in the body and to remove waste products from the cells via urine. When the kidneys are able to function effectively, it allows the liver to continue to do its own job and metabolise excess fat stores.
How much water should you drink?
People often wonder how much water they need to drink every day to stay healthy.
It may seem like an easy question, but it doesn’t necessarily have an easy answer. This is because it depends on a whole host of environmental and physical factors that can vary greatly each day.
Your requirements are impacted by a number of factors, including:
- Sweat levels
- Medical conditions
- Medication use
- Environment (climate)
Some recommendations can be fairly vague, stating you should consume plenty of water, but what is plenty? Others suggest 6-8 glasses of water. The BDA recommends 1.6 litres for women and 2 litres for men. Other methods include basing it on your calorie intake, so 1ml per calorie consumed. Therefore, if you consume 2000kcals per day, you should aim for 2 litres of water per day.
The general rule of thumb equation for fluid intake is (5):
- Body weight (kg) x 0.033 = amount (l)
For example, if you weigh 65kg, you will need just over 2 litres.
However, it is important to make adjustments to this, to factor in sweat levels – for example in the warmer months, on holiday in warm places and if you do a lot of exercise, you will need to drink in excess of the above!
Monitoring your urine colour is an extremely useful way to gauge your hydration levels. The darker the colour, the more dehydrated you are and vice versa.
Top tips for increasing your water intake:
- Buy a reusable water bottle – not only great for the environment but having a bottle to hand will also mean you will have water throughout the day when on the go.
- Refill your water glass when it’s empty- not only is getting up from your desk and moving good for you, but it will also encourage you to drink more regularly.
- Set a water intake goal – try setting yourself a small milestone of drinking 1L by 12noon or setting reminders if you really struggle to remember.
- Jazz up your H20 – if you find it difficult to just drink plain water add some citrus fruits, cucumber or mint to encourage you to drink more.
- Popkin, B., D’Anci, K. and Rosenberg, I., 2010. Water, hydration, and health. Nutrition Reviews, 68(8), pp.439-458.
- Jéquier, E. and Constant, F., 2009. Water as an essential nutrient: the physiological basis of hydration. European Journal of Clinical Nutrition, 64(2), pp.115-123.
- Nissensohn, M., Sánchez-Villegas, A., Galan, P., Turrini, A., Arnault, N., Mistura, L., Ortiz-Andrellucchi, A., Edelenyi, F., D’Addezio, L. and Serra-Majem, L., 2017. Beverage Consumption Habits among the European Population: Association with Total Water and Energy Intakes. Nutrients, 9(4), p.383.
- Riebl, S. and Davy, B., 2013. The Hydration Equation. ACSM’S Health & Fitness Journal, 17(6), pp.21-28.
- Lambert, R., 2021. The Science of Nutrition: Debunk the Diet Myths and Learn How to Eat Well for Health and Happiness. 1st ed. DK, p.25.
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