- The human body comprises around 60% water.
- It’s commonly recommended that you drink eight 8-ounce (237-mL) glasses of water per day (the 8×8 rule).
- Although there’s little science behind this specific rule, staying hydrated is important.
- Here are 7 evidence-based health benefits of drinking plenty of water.
1. Helps maximize physical performance
- If you don’t stay hydrated, your 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 isn’t uncommon for athletes to lose as much as 6–10% of their water weight via sweat.
- This can lead to altered body temperature control, reduced motivation, and increased fatigue. It can also make exercise feel much more difficult, both physically and mentally.
- Optimal hydration has been shown to prevent this from happening, and it may even reduce the oxidative stress that occurs during high-intensity exercise. This isn’t surprising when you consider that muscle is about 80% water.
- If you exercise intensely and tend to sweat, staying hydrated can help you perform at your absolute best.
2. Significantly affects energy levels and brain function
- Your brain is strongly influenced by your hydration status.
- Studies show that even mild dehydration, such as the loss of 1–3% of body weight, can impair many aspects of brain function.
- In a study in young women, researchers found that fluid loss of 1.4% after exercise impaired both mood and concentration. It also increased the frequency of headaches.
- Many members of this same research team conducted a similar study in young men. They found that fluid loss of 1.6% was detrimental to working memory and increased feelings of anxiety and fatigue.
- A fluid loss of 1–3% equals about 1.5–4.5 pounds (0.5–2 kg) of body weight loss for a person weighing 150 pounds (68 kg). This can easily occur through normal daily activities, let alone during exercise or high heat.
- Many other studies, with subjects ranging from children to older adults, have shown that mild dehydration can impair mood, memory, and brain performance.
3. May help prevent and treat headaches
- Dehydration can trigger headaches and migraines in some individuals.
- Research has shown that a headache is one of the most common symptoms of dehydration. For example, a study in 393 people found that 40% of the participants experienced a headache as a result of dehydration.
- What’s more, some studies have shown that drinking water can help relieve headaches in those who experience frequent headaches.
- A study in 102 men found that drinking an additional 50.7 ounces (1.5 liters) of water per day resulted in significant improvements on the Migraine-Specific Quality of Life Scale, a scoring system for migraine symptoms.
- Plus, 47% of the men who drank more water reported headache improvement, while only 25% of the men in the control group reported this effect.
- However, not all studies agree, and researchers have concluded that because of the lack of high-quality studies, more research is needed to confirm how increasing hydration may help improve headache symptoms and decrease headache frequency.
4. May help relieve constipation
- Constipation is a common problem that’s characterized by infrequent bowel movements and difficulty passing stool.
- Increasing fluid intake is often recommended as a part of the treatment protocol, and there’s some evidence to back this up.
- Low water consumption appears to be a risk factor for constipation in both younger and older individuals.
- Increasing hydration may help decrease constipation.
- Mineral water may be a particularly beneficial beverage for those with constipation.
- Studies have shown that mineral water that’s rich in magnesium and sodium improves bowel movement frequency and consistency in people with constipation.
5. 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’s 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. This dilutes the concentration of minerals, so they’re less likely to crystallize and form clumps.
- Water may also help prevent the initial formation of stones, but studies are required to confirm this.
6. 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.
- Although dehydration isn’t the main cause of hangovers, it can cause symptoms like thirst, fatigue, headache, and dry mouth.
- Good ways to reduce hangovers are to drink a glass of water between drinks and have at least one big glass of water before going to bed.
7. Can aid weight loss
- Drinking plenty of water can help you lose weight.
- This is because water can increase satiety and boost your metabolic rate.
- Some evidence suggests that increasing water intake can promote weight loss by slightly increasing your metabolism, which can increase the number of calories you burn on a daily basis.
- A 2013 study in 50 young women with overweight demonstrated that drinking an additional 16.9 ounces (500 mL) of water 3 times per day before meals for 8 weeks led to significant reductions in body weight and body fat compared with their pre-study measurements.
- The timing is important too. Drinking water half an hour before meals are the most effective. It can make you feel more full so that you eat fewer calories.
- In one study, dieters who drank 16.9 ounces (0.5 liters) of water before meals lost 44% more weight over a period of 12 weeks than dieters who didn’t drink water before meals.