Forget 8 Glasses: The New Rule for Staying Hydrated

3. The Science of Thirst: Listening to Your Body's Signals

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With thirst crucial in this regulating process, the human body has evolved a sophisticated system for preserving fluid equilibrium. Knowing the science underlying thirst will enable us to more appropriately handle the fluid requirements of our body. The brain's control centre for several autonomic processes, including fluid balance, the hypothalamus mostly regulates thirst by means of its actions. Even by as little as 1-2% of body weight, sensors in the brain identify changes in blood volume and osmolality—the percentage of dissolved particles in the blood—when the body starts to become dehydrated. These sensors set off our thirst sense, which drives us to hunt for and drink liquids. The brain directs the kidneys concurrently to produce more concentrated urine, therefore conserving water. Usually quite accurate in preserving appropriate hydration, the thirst mechanism is remarkably sensitive. Actually, most healthy people only need drinking in response to thirst to keep appropriate amounts of hydration. Often more dependable than following outside hydration guidelines or schedules, this natural system is quite efficient. Still, thirst isn't always a good gauge of your hydration needs. Sometimes, especially in hot conditions or during vigourous exercise, thirst could trail the body's real fluid needs. You can already be just mildly dehydrated by the time you feel thirsty. This is the reason drinking water before, during, and after exercise is advised even if you don't feel especially thirsty. Reliability of the thirst mechanism can also be influenced by age. Our thirst sense may get less keen as we get older, which would make it more difficult to know when we should drink. Older persons should thus pay especially close attention to their fluid intake and may gain from developing consistent drinking patterns instead of depending just on thirst. Some drugs and diseases can also affect the thirst mechanism or change fluid balance, therefore causing dehydration if not under close control. For example, some blood pressure drugs might compromise kidney function and fluid balance; diabetes can cause urine and fluid loss. Though a vital indication, thirst is not the sole way to gauge hydration level. Another useful clue comes from the colour of urine. While dark yellow or amber-colored urine points to a need for extra fluids, pale yellow urine generally indicates good hydration. This should be taken into account, nevertheless, as several diets, supplements, and drugs might influence urine colour. Maintaining appropriate hydration mostly depends on your learning to understand and react to the signs of thirst from your body. You can create a more natural and customised method to keep hydrated by paying attention to when you feel thirsty, thinking about the elements that might be influencing your fluid needs, and acting pro-actively about hydration in circumstances when you might be at danger of dehydration. Based on the physics of how our bodies control fluid balance, this method—which makes sense—may be significantly more successful than following arbitrary guidelines regarding daily water intake.