Our bodies are around 60% water, give or take. It is
commonly recommended to drink eight 8-ounce
glasses of water per day (the 8×8 rule).
Although there is little science behind this specific
rule, staying hydrated is important.
Here are 7 evidence-based health benefits of
drinking plenty of water.
1. Water Helps to Maximize Physical Performance
If we do not stay hydrated, physical performance can
suffer.
This is particularly important during intense exercise
or high heat.
Dehydration can have a noticeable effect if you lose
as little as 2% of your body’s water content.
However, it is not uncommon for athletes to lose up
to 6-10% of their water weight via sweat.
This can lead to altered body temperature control,
reduced motivation, increased fatigue and make
exercise feel much more difficult, both physically and
mentally.
Optimal hydration has been shown to prevent this
from happening, and may even reduce the oxidative
stress that occurs during high intensity exercise. This
is not surprising when you consider that muscle is
about 80% water.
So, if you exercise intensely and tend to sweat, then
staying hydrated can help you perform at your
absolute best.
Bottom Line: Losing as little as 2% of your body’s
water content can significantly impair physical
performance.
2. Hydration Has a Major Effect on Energy Levels and
Brain Function
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, 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, ranging from children to the
elderly, have shown that mild dehydration can impair
mood, memory and brain performance.
Bottom Line: Mild dehydration (fluid loss of 1-3%)
can impair energy levels and mood, and lead to major
reductions in memory and brain performance.
3. Drinking Water May Help to Prevent and Treat
Headaches
Dehydration can trigger headaches and migraines in
some individuals.
Several studies have shown that water can relieve
headaches in those who are dehydrated.
However, this appears to depend on the type of
headache.
One study of 18 people found that water had no
effect on the frequency of headaches, but did reduce
the intensity and duration somewhat.
Bottom Line: Drinking water can sometimes help
relieve headache symptoms, especially in people who
are dehydrated.
4. Drinking More Water May Help Relieve Constipation
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.
Carbonated water shows particularly promising
results for constipation relief, although the reason is
not entirely understood.
Bottom Line: Drinking plenty of water can help
prevent and relieve constipation, especially in people
who generally do not drink enough water.
5. Drinking Water May Help Treat Kidney Stones
Urinary stones are painful clumps of mineral crystal
that form in the urinary system.
The most common form is kidney stones, which form
in the kidneys.
There is limited evidence that water intake can help
prevent recurrence in people who have previously
gotten kidney stones.
Higher fluid intake increases the volume of urine
passing through the kidneys, which dilutes the
concentration of minerals, so they are less likely to
crystallize and form clumps.
Water may also help prevent the initial formation of
stones, but studies are required to confirm this.
Bottom Line: Increased water intake appears to
decrease the risk of kidney stone formation. More
research is needed in this area.
6. Water Helps Prevent Hangovers
A hangover refers to the unpleasant symptoms
experienced after drinking alcohol.
Alcohol is a diuretic, so it makes you lose more water
than you take in. This can lead to dehydration (24,
25).
Although dehydration is not the main cause of
hangovers, it can cause symptoms like thirst, fatigue,
headache and dry mouth.
A good way to reduce hangovers is to drink a glass of
water between drinks, and to have at least one big
glass of water before going to bed.
Bottom Line: Hangovers are partly caused by
dehydration, and drinking water can help reduce
some of the main symptoms of hangovers.
7. Drinking More Water Can Help With Weight Loss
Drinking plenty of water can help you lose weight.
This is due to the fact that water can increase satiety
and boost your metabolic rate.
In two studies, drinking half a liter (17 ounces) of
water was shown to increase metabolism by 24-30%
for up to 1.5 hours.
This means that drinking 2 liters 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 is the most effective. It can
make you feel more full, so that you eat fewer
calories.
In one study, dieters who drank half a liter 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.