Water makes up about 75 per cent of the human body, so it is important to keep ourselves properly hydrated as we lose water routinely – especially important in the hot summer months. The body loses water when we exhale, sweat, urinate or have a bowel movement, throw up and cry. Therefore, we need to ensure that we are replacing the water we lose in order to prevent dehydration, which occurs when water intake is less than water loss. This is quantified as a one per cent or greater loss of body weight as a result of fluid loss.
- Anyone can become dehydrated, but the young and the elderly are especially susceptible.
- Thirst means you’re already dehydrated. In many experiments, just one to two per cent dehydration has been shown to trigger thirst. This level of dehydration can happen quickly, especially following intense exercise or when battling viruses.
- Symptoms and signs of dehydration range from minor to life-threatening. The early symptoms of dehydration are thirst and reduced urine output and darkening of the urine. As dehydration progresses, other symptoms develop, including
- dry mouth
- muscle cramps
- weakness, and more
- Fatigue is a common dehydration symptom. A pair of recent US studies found that young people who were mildly dehydrated were much more likely to feel fatigued during moderate exercise and even when sedentary.
- Dehydration causes foggy memory, irritability, and anxiety. Even mild dehydration puts stress on the body’s cognitive functioning. Studies have linked dehydration to a drop in concentration and short-term memory in young adults, as well as an increase in feelings of anxiety and irritability. With children, studies are more conclusive that hydration can improve attention and memory.
So, how much water should you be drinking? The formula for daily fluid requirements depends upon an individual’s weight. Here’s a simple chart from medicinet.com: