There are many claims that increased water intake may reduce body weight by increasing your metabolism and reducing your appetite.

According to two studies, drinking 17 ounces (500 ml) of water can temporarily boost metabolism by 24–30% 

The image below shows this effect. The top line shows how 17 ounces (500 ml) of water increased metabolism. Notice how this effect decreases before the 90-minute mark 

The researchers estimated that drinking 68 ounces (2 liters) in one day increased energy expenditure by about 96 calories per day.

Additionally, it may be beneficial to drink cold water because your body will need to expend more calories to heat the water to body temperature.

Drinking water about a half hour before meals can also reduce the number of calories you end up consuming, especially in older individuals 

One study showed that dieters who drank 17 ounces (500 ml) of water before each meal lost 44% more weight over 12 weeks, compared to those who didn’t (12Trusted Source).

Overall, it seems that drinking adequate amounts of water, particularly before meals, may have a significant weight loss benefit, especially when combined with a healthy diet.

What’s more, adequate water intake has a number of other health benefits.

SUMMARY

Drinking water can cause mild, temporary increases in metabolism, and drinking it about a half hour before each meal can make you automatically eat fewer calories. Both of these effects contribute to weight loss.