Adults need water or similar suitable beverages such as sodium-free mineral water, low-fat dairy products or fortified, non-sugary plant-based drinks on average 1-1.5 liters per day, all year round. This represents the amount of water from beverages alone, and additionally water is needed from foods so that the total water intake would be 2 liters per day for women and 2.5 liters per day for men.
The amount of water needed from food can be easily obtained by consuming the recommended amount of at least half a kilo of fruit and vegetables per day. If a person's diet does not include water-rich vegetable products, or if they consume high levels of natural diuretics such as caffeine or alcohol, they may need to increase their water intake. The need also increases with sweating, heat or some medical conditions.
Insufficient hydration affects the mind and body
Water is essential for humans. It maintains the body's fluid balance, regulates body temperature, aids digestion, transports and absorbs nutrients and removes metabolic waste products. Children and the elderly in particular are often reminded to drink water, but there are also many surprising health benefits to drinking enough water for the working age population. Adequate hydration improves cognitive performance in tasks involving attention, motor coordination or executive function.
Inadequate water intake can also affect mood. Indeed, dehydration has been found to be linked to mood, increasing feelings of anger, confusion, tension and fatigue. Adequate drinking also reduces the risk of kidney stones. Switching from sugary drinks to sugar-free drinks such as water supports weight management and helps reduce daily energy intake. In addition, drinking enough water can help reduce the amount of adipose tissue as part of a lifestyle change in overweight people. Two intervention studies (study 1 & study 2) compared groups who followed an otherwise similar, low-energy diet, but one group drank more water. Both groups lost weight, but those who drank more water (1300ml vs. 300-450ml) lost more weight.
Drinking habits are discussed in the nutritional guidance sessions
The RAVI project is a nutrition research project funded by the European Regional Development Fund (ERDF) and carried out by Satakunta University of Applied Sciences between 2023 and 2026. The RAVI project will investigate the impact of personalized nutrition guidance on the well-being and work ability of employees. The RAVI study has been running in the Satakunta region for a year. The study has so far organized almost 250 nutrition guidance sessions, that have included discussions on adequate hydration. Laboratory results collected from the study subjects are viewed in the sessions. The lab results can provide clues that the study subjects may not be drinking enough. Hematocrit and hemoglobin levels can be elevated due to several reasons, dehydration being one of them. Laboratory tests are not used to make any diagnosis, but the results are useful in the conversations when determining the subjects’ drinking habits.
Importance of hydration in sports
If you like sports, drinking enough water will improve your performance, especially during strenuous exercise and in warm weather. In addition to the improved cognitive functions mentioned above, good hydration enhances muscle endurance by improving the transport of oxygen and nutrients to the muscles, for example. Adequate hydration also reduces unnecessary stress on the heart muscle. If you engage in endurance sports, adequate hydration is also extremely important because it improves the amount and availability of glucose stored in the muscles. Also, the joints of (recreational) athletes are more protected by good hydration. Dehydration can reduce the amount of synovial fluid, resulting in stiffer and less flexible joints and an increased risk of joint pain and injury.
Overhydration should be avoided
Although water is essential for life, and is involved in almost all bodily functions, it is also possible to drink too much water. In healthy people, the electrolyte balance often remains good, even if you drink a lot of water over several hours. However, drinking too much water quickly is dangerous. The body does not have time to adapt to the rapid changes and blood sodium levels become diluted. This condition is also known as water intoxication. The situation is made worse if sodium has been lost simultaneously, for example due to prolonged exercise or illness. Even if you exercise a lot, it is possible to overestimate your sweat rate. Women in particular are more prone to overdrinking because they have less body surface area and sweat less than men. You can get water intoxication even without touching water. If you have sweated profusely during a physically strenuous day at work and then continue straight to a night out, drinking a lot of alcohol beverages e.g. beer can also cause an electrolyte imbalance. Many patients recover after they stop drinking, but water intoxication can be fatal in the worst cases. It is a good idea to seek treatment if you feel unusually unwell after drinking a lot of water.
How to hydrate correctly?
It is important to remember that you should not make any drastic changes when it comes to hydrating. If you think you don’t drink enough, you could start by adding a couple of glasses of water and plenty of fruit and vegetables to your day. Drinking steadily throughout the day is safer and more effective than refueling in one go. If physical exertion is prolonged and sweating is high, it is also better to drink beverages containing electrolytes (sodium, chloride, potassium, magnesium, calcium), which also prevent muscle cramps. Pale or light yellow and plentiful urine is often an indication that you are well hydrated. Additionally, a healthy diet helps to maintain electrolyte balance. It is also worth mentioning that the health benefits of drinking water have been found in studies that have improved a state of dehydration. Hence, drinking more than you need does not provide additional benefits - on the contrary, it's not fun to be constantly flushing the toilet. So, remember to keep calm and drink adequately!
Did you know? Tips to increase your water intake
- Keep a water bottle at your desk to sip throughout the day or with you when leaving the house.
- Set a timer on your phone or use a water-tracking app.
- Always drink a full glass of water after a meal and a coffee break.