The human body is roughly 60% water. The common recommendation is to drink eight 8-ounce glasses of water per day. This particular figure does not have a great deal of science behind it, staying hydrated is however important.
Here are a selection of evidence-based health benefits of staying hydrated.
Maximum physical performance.
Physical performance can suffer greatly from a lack of hydration.
During intense exercise or while exercising in high heat this is even more the case.
Losing as little as 2% of your body’s water content can have a noticeable effect on you. It is not uncommon for athletes to lose anywhere up to 10% of their water weight through sweating, therefore adequate hydration is vital.
Even though the body as a whole is 60% water, muscle is around 80%, so water intake is far more important when the muscles are being worked hard.
Help with weight loss.
Drinking half a litre of water has been shown to increase metabolism by 24-30% for up to an hour and a half after drinking it.
That means that drinking 2 litres of water a day can up your energy expenditure by almost 100 calories per day.
Drinking water half an hour before a meal has been shown to decrease the the amount of food you eat at meal times by making you feel fuller. In one study, dieters who drank half a litre of water before meals lost an average of 44% more weight over the course of 12 weeks.
For the biggest benefit, water should be drunk cold. This way the body burns more calories to heat the water to body temperature.
Fluid loss of as little as 1.3% has been shown to impair brain function. Especially affected are concentration and mood. Other studies have shown that similar levels of fluid loss have had a detrimental affect on working memory and increased feelings of fatigue and anxiety.
Loss levels this low are to be expected in just day to day life, if putting high heat and exercise into the mix it is clear that improper hydration can have big effects on your health.
Below are some links to some of the studies and evidence mentioned in this post.
NCBI – Hydration and physical performance
NCBI – Water, Hydration and health
NCBI – Dehydration influences mood and cognition
NCBI – water induced thermogenesis
Nutrition.org – Healthy hydration guide