Don’t Rely on Thirst as the Best Indicator of Hydration

Quick Read – 2 minutes


The human body is composed of 60% water. Despite water being essential for our survival, it is often a forgotten nutrient. We usually only consider having a drink of water when thirsty. However, by the time you feel thirst you could already be dehydrated, having lost as much as 1-2% of the body's water content.

Feeling thirsty is the most noticeable indication that you are experiencing mild dehydration. When your body starts to run low on water, a series of changes take place. The body can compensate for water loss to some extent by altering heart rate and blood pressure, and by adjusting kidney function to retain more water. Thirst stimulates the need to drink; as a result, water intake is increased and the water balance of the body is restored.

With mild water loss, it is common to experience more stress and forgetfulness. Physical symptoms of mild dehydration can include tiredness, little or no urine, dry mouth, headaches, weakness, and dizziness. Increased levels of dehydration with water loss of more than 2% can lead to a reduction in physical performance and reduced ability to control body temperature.


The best way of staying hydrated is to drink before you feel thirsty - regularly sipping at drinks throughout the day especially after exercise, or in hot weather.

Data Source:

The Mayo Foundation for Medical Education and Research