The body is 60% water by weight

Our bodies contain a lot of water — 60% of an adult’s weight, and 80% of a newborn’s weight, is bodily fluid. In other words, the body of a 70 kg man contains about 42 L of water.

The water we drink is absorbed by the intestines, and circulated throughout the body in the form of fluids such as blood.

These perform various functions to keep us alive. They deliver oxygen and nutrients to the cells and take away waste materials, which are then eliminated with urination. When the body temperature rises, blood circulation to the skin increases, enabling heat dissipation through sweating, helping to keep the body at a constant temperature.

Why do we get thirsty? It is a signal that our body is dehydrated.

There are two types of thirst. The first occurs when the body has lost fluid due to sweating or other causes. The other type of thirst occurs when the concentration of bodily fluid (water and ions) is out of balance.

When it is hot, the body temperature is regulated through sweating. In order for this mechanism to function properly, the body needs to have enough fluid and a proper balance of water and ions, meaning that it is important that the concentration of the bodily fluid always remains constant.

When we sweat, we lose water and ions — mostly sodium and chloride (salt). If you drink just water to replenish lost fluid, the balance of water and ions in the body breaks down, and the osmolality (level of electrolytes in the bodily fluid) gradually decreases. In order to halt this trend, your body automatically stops the feeling of thirst, and seeks to eliminate excess water as urine. As a result, the normal bodily fluid level is not sufficiently replenished. This phenomenon is called spontaneous dehydration.

The reason that sweat tastes salty is that it contains not just water but also other Ions. Therefore, it is best to drink something that can help your body quickly replenish both the water and Ions that it has lost through sweating.

You can rehydrate effectively by consuming a rehydration drink which has the components that are close to your body fluids.