Since water is naturally calorie-free, it is generally linked with reduced calorie intake.
Observational studies have shown that people who drink mostly water have up to a 9% (or 200 calories) lower calorie intake, on average (16, 17).
Drinking water may also help prevent long-term weight gain. In general, the average person gains about 1.45 kg (3.2 lbs) every 4 years (18).
It is especially important to encourage children to drink water, as it can help prevent them from becoming overweight or obese (17, 3).
A recent, school-based study aimed to reduce obesity rates by encouraging children to drink water. They installed water fountains in 17 schools and provided classroom lessons about water consumption for 2nd and 3rd graders.
After one school year, the risk of obesity had been reduced by a whopping 31% in the schools where water intake was increased (19).
How Much Water Should You Drink?
Many health authorities recommend drinking eight, 8-oz glasses of water (about 2 liters) per day.
However, this number is completely random. As with so many things, water requirements depend entirely on the individual (20).
For example, people who sweat a lot or exercise regularly may need more water than those who are not very active.
Older people and breast-feeding mothers also need to monitor their water intake more closely (21).
Keep in mind that you also get water from many foods and beverages, such as coffee, tea, meat, fish, milk, and especially fruits and vegetables.
As a good rule of thumb, you should always drink water when you're thirsty, and drink enough to quench your thirst.
If you find you have a headache, are in a bad mood, are constantly hungry or have trouble concentrating, then you may suffer from mild dehydration. Drinking more water may help fix this (22, 23, 24).
Based on the studies, drinking 1-2 liters of water per day should be sufficient to help with weight loss.
Here's how much water you should drink, in different measurements:
Glasses (8-oz): 4–8.
However, this is just a general guideline. Some people may need less, while others may need a lot more.
Also, it is not recommended to drink too much water either, as it may cause water toxicity. This has even caused death in extreme cases, such as during water drinking contests.
BOTTOM LINE: According to the studies, 1–2 liters of water per day is enough to assist with weight loss, especially when consumed before meals.
Water can be really helpful for weight loss.
It is 100% calorie-free, helps you burn more calories and may even suppress your appetite if consumed before meals.
The benefits are even greater when you replace sugary beverages with water. It is a very easy way to cut back on sugar and calories.
However, keep in mind that you're going to have to do a lot more than just drink water if you need to lose a significant amount of weight.
Water is just one, very small piece of the puzzle.