Is thirst a good predictor of dehydration?

Water is essential for daily functioning and health, and we can only survive a few days without. Yet we continually lose water through sweat, urination and even evaporation when we breathe.

This is why we have evolved a way to regulate and maintain water levels in our bodies. Like other animals, our survival depends on a strong biological drive that tells us to find and drink water to balance fluid loss.

This is thirst – a dry feeling in the mouth that signals that we need to drink something. This basic physiological mechanism is controlled primarily by part of the brain’s “control center,” the hypothalamus. The hypothalamus receives signals from different parts of the body and in return releases hormones that act as a messenger to signal the feeling of thirst.

What is dehydration?

Staying hydrated (having enough water in our body) is important for various reasonsincluded:

• regulating body temperature through sweat and breathing
• lubricating joints and eyes
• preventing infections
• digest and absorb nutrients
• flushing out waste (via the kidneys)
• preventing constipation
• brain function (including memory and concentration)
• mood and energy level
• physical performance and recovery after exercise
• skin health.

Dehydration occurs when our body does not have enough water. Even small drops in fluid level have that effect noticeable consequencessuch as headache, dizziness, lethargy and difficulty concentrating.

Chronic dehydration can pose more serious health risks, including urinary tract infections, constipation and kidney stones.

What does the evidence say?

Despite thirst being one of the most fundamental biological drivers of proper hydration, science suggests that our feelings of thirst and subsequent fluid intake do not always correlate with hydration levels.

For example, a recent study examined the impact of thirst on fluid intake and hydration status. Participants went to a laboratory in the morning and later in the afternoon to provide markers of hydration status (such as urine, blood samples and body weight). The relationship between morning thirst and afternoon hydration status was negligible.

Furthermore, thirst can be caused by environmental factors, such as access to water. For example, one study looked at whether ample access to water in a laboratory affected how much people drank and how hydrated they were. The link between how thirsty they felt and how hydrated they were was weak, suggesting that water availability affected their fluid intake more than thirst.

You can also practice change our thirst mechanismalthough studies are limited at this stage.

Interestingly, research shows that women experience greater thirst than men, regardless of hydration status. To understand Gender differences in thirstresearchers provided men and women with fluids and then measured their thirst and how hydrated they were. They found that women generally reported thirst at lower levels of fluid loss. Women also appear to respond more to get thirsty by drinking more water.

Other ways to determine if you need to drink some water

Although we recognize that some people will need to drink more or less many peopleEight cups (or two liters) a day is a good amount of water to aim for.

But besides thirst, there are many more ways to determine whether you should drink more water.

1. urine color: light yellow urine generally indicates good hydration, while darker, concentrated urine indicates dehydration

2. frequency of going to the toilet: urinating regularly (about four to six times a day) indicates good hydration. Irregular urination can indicate dehydration

3. skin turgor test: carefully pinching the skin (e.g. on the back of the hand) and observing how quickly the skin returns to its normal position can help assess hydration. A slow return may indicate dehydration

4. Mouth and Lips: Dry mouth or cracked lips can be early signs of dehydration

5. Headaches and Fatigue: this may include frequent headaches, dizziness or unexplained fatigue signs of insufficient hydration

6. sweating: In physically active people, monitoring how much they sweat during activity can help estimate fluid loss and hydration needs. Higher sweat levels can predispose a person to dehydration if he or she is unable to replenish the fluids lost through water intake

These indicators, used together, provide a more comprehensive picture of hydration, without relying solely on the feeling of thirst.

Of course, if you are thirsty, it is still a good idea to drink some water.