Not consuming 2 liters of plain water daily is not a sign of weakness, but rather an indication that the body's water regulation system is functioning effectively. Biological mechanisms, such as reduced thirst, increased urine excretion, and a sensation of fullness, are designed to prevent the body from absorbing too much water in a short period.

Water is essential for survival, and the body employs strict control mechanisms. Even a slight increase in blood salt concentration prompts the brain to signal thirst, encouraging water intake. Conversely, when the body has received sufficient water, "thirst-off" signals activate rapidly. Just a few signals from the mouth, throat, and stomach upon drinking water allow the brain to recognize impending rehydration. Consequently, thirst diminishes even before water is fully absorbed. Simultaneously, the kidneys increase urine output to maintain fluid balance.

Neuroscience research indicates that when the body is adequately hydrated, swallowing additional liquid becomes noticeably more difficult. This explains why many people find it challenging to drink more water after consuming a large amount.

Another factor is the sensation of stomach distension. Continuous water intake quickly expands the stomach, creating a feeling of fullness. Physiological tests show that many individuals begin to feel "water-full" after approximately 400-700 ml.

Alcohol (ethanol) is a central nervous system depressant. Photo: Anh Thu

In contrast to plain water, beer affects the body in ways that encourage greater consumption. Beer is often served cold, carbonated, and features distinct flavors. These elements enhance refreshment and ease of drinking. The carbon dioxide in beer can also induce burping, which helps alleviate stomach pressure, making drinkers feel "lighter" despite a substantial liquid intake.

A second factor is alcohol's impact on the brain. Ethanol in beer is a psychoactive substance capable of activating the brain's reward system, particularly the dopamine system. The mere smell or taste of beer can heighten the desire to drink more, even before the alcohol content is sufficient to cause intoxication.

Furthermore, alcohol impairs behavioral control. As blood alcohol concentration rises, the brain becomes less sensitive to internal signals such as stomach fullness or a sense of "enough". This makes it easier for drinkers to continue consuming alcohol even when their body is becoming overloaded. Prolonged, heavy beer consumption can lead to significant alcohol intake, resulting in dehydration, electrolyte imbalance, and various other health risks.

Doctor Nguyen Huy Hoang

Vietnam Association of Underwater and Hyperbaric Medicine