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CLINICAL KNOWLEDGE MAGAZINE
7 min read
How to Ensure Proper Hydration During Heatwaves
David Janitzek
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Diets Premium Medical Expert • 25.09.2026
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Scientifically reviewed by a clinical dietitian:
This article has been peer-reviewed for adherence to IŻŻ, WHO, and PTGiP clinical nutritional standards.
| CLINICAL KNOWLEDGE MAGAZINE CLINICAL KNOWLEDGE MAGAZINE | min read 7 min |
| Diets Premium Medical Expert David Janitzek | Scientifically reviewed by a clinical dietitian 25.09.2026 |
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Key Takeaways
Ensuring appropriate hydration of the body enables it to better cope with all challenges. It is important to ensure a sufficient intake of fluids during both the summer and winter seasons, but special attention should be paid to days when the temperature is higher than usual.
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The fundamental role of water in human physiological function: essential mechanisms and consequences of hydration imbalance
Water constitutes an indispensable component of the human body, comprising approximately 75% of total body mass in newborns and declining to roughly 50–60% in adults, with a progressive reduction observed with advancing age (Łubkowska, 2016). It fulfills irreplaceable roles in regulating metabolic processes, including the facilitation of enzymatic reactions, maintenance of thermoregulation, and the transportation of electrolytes and nutrients via the circulatory and lymphatic systems. Adequate hydration is furthermore critical for musculoskeletal system efficiency, influencing connective tissue elasticity and the transmission of neural signals. Insufficient fluid intake—particularly under conditions of elevated physical exertion or high ambient temperatures—may result in dehydration, manifesting as cognitive impairment, diminished physical performance, and, in extreme cases (exceeding 20% loss of total body water), life-threatening complications (Skotnicka et al., 2016). Conversely, excessive water consumption, though less common, can induce a state of overhydration, characterized by hyponatremia (reduced blood sodium concentration), tissue edema, and elevated arterial pressure, which in severe instances may also prove fatal (Okręglicka et al., 2017).
Is there truly a definitive answer to how much water one should consume daily?
The human body renews its water reserves on average every three weeks or so. To sustain hydrological equilibrium, consistent fluid replenishment is essential, taking into account individual variables such as age bracket, intensity of physical exertion, ambient thermal conditions, and atmospheric moisture levels. Each of these factors contributes to the final requirement, meaning that the optimal water intake can vary significantly from person to person. According to expert guidelines, the daily fluid consumption (from both beverages and solid foods) for women should amount to approximately two liters. During pregnancy and breastfeeding, this recommended intake increases to 2.3 liters and 2.7 liters per day, respectively. For men, the optimal quantity is 2.5 liters. In children, fluid intake should be gradually increased in proportion to their physiological development (source: Jarosz et al., 2020). A commonly cited general recommendation suggests that the minimum daily fluid intake should be around 2.5 liters, though this figure represents an average and does not account for individual variations. Alternative calculation methods include 1 milliliter of fluid per kilocalorie consumed or 30 milliliters per kilogram of body weight (Skotnicka, Rhode, Kłobukowski, 2016).
How to effectively maintain optimal body hydration during periods of intense heat?
During periods of extreme heat, it is essential to adjust fluid intake according to ambient temperatures. Increased perspiration leads to significant water loss, which may result in symptoms such as dizziness, nausea, or even fainting in severe cases. Health professionals recommend increasing daily fluid consumption by at least one liter beyond the usual requirement. The most suitable option remains medium- or highly mineralized water, rich in essential electrolytes like magnesium and calcium—with the caveat that individuals with kidney dysfunction should avoid highly mineralized varieties. Mineralization levels are categorized based on ion concentration: below 500 mg/l for low-mineralized, 500–1500 mg/l for medium-mineralized, and above 1500 mg/l for high-mineralized waters. To enhance palatability, water can be infused with citrus slices, raspberries, or fresh herbs, which not only diversify the flavor but also provide additional vitamins. Isotonic beverages effectively replenish lost electrolytes and are recommended not only for athletes but also for anyone exposed to high temperatures. Additionally, many fruits and vegetables, such as watermelons, cucumbers, and tomatoes, contain substantial water content and can serve as valuable sources of hydration and nutrients.
The harmful consequences of alcohol consumption during high temperatures: dehydration, health hazards, and hidden calories
Consuming chilled alcoholic beverages on hot days may seem like a reasonable way to cool down, yet in reality, it accelerates the body’s dehydration process. Alcohol acts as a diuretic, leading to increased fluid and electrolyte loss—both through more frequent urination and heightened perspiration. Additionally, intoxication resulting from excessive alcohol consumption significantly raises the risk of accidents, particularly near bodies of water. It is also important to note that alcoholic drinks provide so-called "empty calories"—they are energy-dense but nutrient-poor. An alternative may be alcohol-free beers, which, according to research, exhibit properties similar to isotonic drinks; however, their regular consumption is not recommended. The optimal solution remains water.
Comprehensive Guide to Hydration During Periods of Elevated Heat Exposure
Under conditions of elevated ambient temperature, the most advantageous options for maintaining adequate fluid balance are pure spring water or purpose-formulated isotonic solutions. These preparations not only effectively quench thirst but also facilitate precise replenishment of electrolytes and trace elements excreted through perspiration. Medical professionals uniformly emphasize that the consumption of alcoholic beverages during heatwaves constitutes a particularly irresponsible practice, as it exacerbates dehydration and disrupts the body’s thermoregulatory mechanisms.
David Janitzek
Diets Premium Medical Expert
Member of the Diets Premium clinical editorial board. Specializes in medical diet therapy, metabolic health, and nutritional planning.
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