Our bodies are approximately 60% water. It really is like a magic potion helping to maintain and repair your body and even your brain.

Losing as little as 2% of your body’s water content can significantly impair physical performance, but by the time your brain sends the message that you are thirsty, the dehydration process has already started.

Your brain is strongly influenced by hydration status. Studies show that even mild dehydration (1-3% of body weight) can impair many aspects of brain function.

In a study of young women, a fluid loss of 1.36% after exercise impaired both mood and concentration and increased the frequency of headaches.

Another similar study, this time in young men, showed that fluid loss of 1.59% was detrimental to working memory and increased feelings of anxiety and fatigue.

A 1-3% fluid loss equals about 1.5-4.5 lbs (0.5-2 kg) of body weight loss for a 150 lbs (68 kg) person. This can easily occur through normal daily activities, let alone during exercise or high heat.

Many other studies, across all genders and age groups, have shown that mild dehydration can impair mood, memory and brain performance

Constipation is a common problem, characterized by infrequent bowel movements and difficulty passing stool. Increasing fluid intake is often recommended as a part of the treatment protocol, and there is some evidence to back this up. Low water consumption appears to be a risk factor for constipation in both young and elderly individuals

Studies have shown that drinking plenty of water can help with weight loss. This is due to the fact that water can increase satiety and boost your metabolic rate. In two studies, drinking half a litre (17 ounces) of water was shown to increase metabolism by 24-30% for up to 1.5 hours. This means that drinking 2 litres of water every day can increase your total energy expenditure by up to 96 calories per day. The timing is important too and drinking water half an hour before meals are the most effective. It can make you feel fuller so that you eat fewer calories. In one study, dieters who drank half a litre of water before meals lost 44% more weight, over a period of 12 weeks. It is actually best to drink water cold because then the body will use additional energy (calories) to heat the water to body temperature.