All you need to know about hydration

The adult human body can survive only around 3-4 days without water. On the other hand, without food intake, it is possible to remain for about 3 weeks. On average, 60% of the body is water. Even slight dehydration may cause a decrease in physical and mental performance. For this reason, the first component of a healthy diet is proper hydration. In this article, I will help you to understand this statement, and advise you which beverages to drink and which to avoid. Let’s begin!

What Is The Water Responsible For In The Organism?

Dehydration Impacts Cognitive Performance

More and more of contemporary literature is leaning towards that insufficient amount of water may affect our intellect. One of the meta-analysis performed on 33 studies, proved that water deficiency over 2% impairs our performance in the tasks that require concentration, executive abilities, and motor coordination1.

In another study, 20 women participated in 2 randomized sessions of 24h of controlled dehydration. The authors conclusion was that in case of our mood, mild dehydration has the biggest influence on watchfulness and sleepiness.  However, these side effects were quickly mitigated, soon after the subjects were allowed to drink again2. In fact, for water to arrive from the mouth to the bloodstream, the body needs only 5 minutes3.

Dehydration And Physical Performance

Losing 1-2% of body weight in form of liquid can negatively affect endurance capabilities. A higher level of dehydration (4%) may cause cramps and loss of optimal strength and coordination. Challenging training in hot temperatures can result in 2-3 liters of liquid loss per hour.

If you are an active person you should bear in mind 2 things. Firstly, do not react to dehydration but prevent it. Secondly, if your training is demanding and/or you perform it in extreme weather conditions and that causes excessive sweating, pouring tons of water at once may not be sufficient to replenish the liquid level. The body does not want to absorb the liquid if the level of electrolytes is improper. According to studies, a higher amount of sodium may prevent excessive urine excerption a few hours after the workout4.

A good way to prevent dehydration during and after a challenging training session is to prepare a homemade isotonic drink. It is enough to combine honey, lemon and add a pinch of salt to it. I suggest a homemade version, because of the certainty of natural ingredients – most of the commercial sport drinks have added sugar and other unnecessary ingredients, so if you decide to buy them check the label first.

Dehydration Symptoms

Humans have a strong survival instinct, and because of the importance of water in the organism, it is very easy to self-diagnose its deficiency. It is obvious that the first symptom is thirst. Overdried mouth, lips, eyes, and mucosa are strong evidence to grab and drink a glass of water. Personally, after every wake-up, I take around 10 gulps of water to literally unglue my stuck eyes and awake the rest of the body. And what about alcohol?

Why during a hangover, we have headaches? Dehydration causes the brain to shrink, thereby triggering the pain receptors. Therefore, not reasonless the day after heavy alcohol consumption the thirst skyrockets.

Another easy hydration level indicator is the urine color. A straw color is considered as a the healthiest one and means you are well-hydrated. Darker shades of yellow are signs of dehydration. Additionally, a strong smell usually accompanies the darker color. Of course, bear in mind that some foods are affecting both, the color and smell, such as: beetroots in case of the first, and asparagus of the second. Frequency also matters – it has been established that a healthy person pees from 4 to 10 times a day. (

What To Drink?

1. Water – the number one choice, undoubtedly everyone should drink it. Eventually you are almost all made of water! The main minerals that you get from the water are: calcium, magnesium, phosphorus and potassium. I choose a filtered tap water, which is more economic and environmental-friendly. Of course, in this case, get certainty that the one running through the pipes of your building is drinkable (you should be also able to verify its mineralization on the distributor’s website).The bottled one should have more minerals instead, but their concentration is different, depending on the brand, so read well the labels.

Still or sparkling?  In case I buy one, I always choose the plain water to hydrate myself better. Even though carbonated one might be beneficial for those who want to lose weight (feeling of satiation), I’d stick to the still water that has no side effects in form of burping or bloating.

2. Tea – in the beginning, for the sake of clarity, the statement that it’s dehydrating is a myth. Even though, it has diuretic properties, it doesn’t appear to cause excessive fluid loss. In one controlled trial the subjects in 2 groups were given respectively the same amounts of water and black tea for 12h – the outcome showed they have similar hydrating properties5.

Probably the healthiest of the teas is green tea. It contains: catechins (polyphenol), caffeine, theanine, saponins, vitamin C, vitamin B2, a lot of minerals, and more. This list is a reason why green tea lowers body fat, cholesterol, blood pressure and blood sugar. But that’s not all – it may also prevent from cognitive decline and breast cancer6.

However, if you like to drink the tea with lemon, the white tea appears to be even healthier, because of more phytonutrients that are released only in a certain pH level.

I also recommend yerba mate – I drink it almost every day. It contains polyphenols, vitamins, minerals and a lot of caffeine. I find it a better friend than coffee while working. But…

3. Coffee – my girlfriend is Italian, so I cannot skip this one… But being fully serious, also drinking coffee has a lot of benefits. For instance, it plays a role in decreasing the risk of chronic liver disease. In 1 study the participants prone to develop such disease through excessive alcohol consumption or obesity were divided into 2 groups. In result, those who drank over 2 cups of coffee a day had less than half the risk of liver disease in comparison to the ones that drank less than 1 cup/day7. Coffee consumption may also decrease the depression risk8.

Coffee and tea have a lot of antioxidants that are responsible for inhibiting the process of oxidation in the body by fighting with free radicals (the cruel enemies that can damage our body cells). In other words – if you want to live longer, consider drinking tea and coffee!

4. Fresh smoothies/juices – no doubts veggies and fruits are always the leading products when it comes to stay healthy and take care about the right micronutrients intake. The difference between smoothies and juices is that the first one is a way healthier option, because in smoothies all the pulp (fiber) and more antioxidants is drank.

Drinking smoothies helps to keep the blood sugar level low in comparison to pure juices with no fiber. Of course, the fresh homemade juice is also a great beverage, but watch out on the amount of sugar if it’s mainly composed of fruits. Another advantage of smoothie is that you can combine it with nuts, peanut butter, milk, protein powder etc., which transforms it into a fully nutritious meal.

5. Milk – it’s true that dairy milk is full of nutrients, such as: calcium, phosphorous, potassium, magnesium, proteins, carbs, and fats. However, there is a lot of controversy in the research if it’s more healthy than harmful, because of cancerogenic effects. For this reason, I do not limit myself to drink cow’s milk only, but rather I am using it interchangeably with plant-based milk.

Additionally, if you don’t feel the best after eating dairy products, consider a lactose intolerance, since one metanalysis showed that as much as 68% of the population is lactose intolerant9.

Fortified oat, almond, or coconut milk can be also healthy and reach in vitamins and minerals, similar to dairy milk.

Even though milk can be a healthy beverage, watch out for the amounts you consume and keep in mind the calorie intake. Cow’s milk 3,2% fat has 61 kcal/100ml. In the case of plant-based milk always choose the ones without added sugar.

Which Beverages To Avoid?

There are thousands of different beverages on the shop shelves, but the biggest problem of most is the amount of sugar, sweeteners, preservatives, and other chemicals they contain. Avoid drinking flavored water – except the amount of water itself, usually, it has around 5% of sugar in the composition or unhealthy sweeteners. Therefore, in the 2,5l bottle, you can find around 20-25 teaspoons of sugar. To compare, WHO recommends the intake of a maximum 5-10 teaspoons of added sugar a day.  If you don’t like unflavored water, make yourself a homemade flavored one with added fruits, herbs, honey, or healthy sweeteners with a reasonable amount.

For similar reasons, on the daily basis, you should avoid fizzy drinks. Not accidentally, the coke in Poland got much more expensive together with the sugar tax increase. They are as well very caloric, with tons of sugar and chemicals, for instance: glucose-fructose syrup, acesulfame K or aspartame.

If you buy supermarket juices, because you don’t have time or equipment to make them at home, read the labels to avoid the same unhealthy set of ingredients as in the before-mentioned beverages. Choose only the ones made with 100% fruits/vegetables. And be reasonable with the quantity drank per day, because as I mentioned before, it can easily increase the blood sugar level. You can always support yourself with a glycemic index table to find out which juices are safer in bigger quantities.

How Much To Drink?

Recommendations are different – 8 glasses water/day or 2-3l for example. The point is that it depends on the lifestyle, body weight, and weather conditions. The most important is to incorporate a habit of drinking water every day.

Just listen to your body and provide it with the necessary amount of fluid. Don’t let yourself get any of the symptoms of dehydration mentioned earlier, and you’ll be fine. And if you are struggling with fat loss, consider that sometimes the body is tricking you and instead of food, all you need to do is drink something.

Also keep in mind that you also deliver water through eating, especially vegetables and fruits. For instance, cucumber is composed of 96% water, watermelon is 92%, apple is 85%. Therefore, a combination of healthy habits is the best way to avoid dehydration.

In the case of caffeinated drinks, also don’t exaggerate – Food and Drug Administration (American government institution) states that 300-400 mg/day is not harmful to a healthy adult, which is equal to 3-4 cups of coffee. Drinking caffeine may be also very beneficial for athletic performance – for this reason, for instance, Olympic Weightlifters can have a maximum of 12mg/ml of it in excreted urine. In addition, to not let caffeine affect your sleep quality, you should avoid it around from around 5-6h before bedtime.


One thing can be said – water is life. It’s an essential part of many processes in the human body and therefore crucial for wellbeing maintenance. We live in a generation full of stressors all around, which often makes us forget the most basic, however important things. Nevertheless, I hope that thanks to this article from now on you will always remember about water in your everyday life, as well as about to make wise choices when it comes to what you drink. Thus, hydrate yourself well and enjoy life at full performance!


  1. Wittbrodt MT et al., Dehydration Impairs Cognitive Performance: A Meta-analysis, 2018
  2. Pross N. et al., Influence of progressive fluid restriction on mood and physiological markers of dehydration in women, 2013
  3. Péronnet F et al., Pharmacokinetic analysis of absorption, distribution and disappearance of ingested water labeled with D₂O in humans, 2011
  4. Tudor Bompa and Carlo A, Buzzichelli, Periodization Training for Sports, 2015
  5. Ruxton CH, Hart VA, Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trial, 2011
  6. Michael Greger, How not to die, 2015
  7. Ruhl CE, Everhart JE, Coffee and tea consumption are associated with a lower incidence of chronic liver disease in the United States, 2005
  8. Lucas M. et al., Coffee, caffeine, and risk of depression among women, 2011
  9. Storhaug CL, Fosse SK, Fadnes LT., Country, regional, and global estimates for lactose malabsorption in adults: a systematic review and meta-analysis, 2017

2 thoughts on “All you need to know about hydration”

  1. Wonderful article! It is not easy to find texts well written like this online, with citations and good scientific info. Thanks a lot! Looking forward to read the next one…

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