People who drank water before all three main meals reported a loss of 4.3 kg over the 12 weeks, whereas those who did not drink water lost an average of 0.8kg.

Adults in the group who were instructed to 'preload' with water lost, on average, 1.3 kg more than those in the control group. People who reported preloading before all three main meals in the day reported a loss of 4.3 kg over the 12 weeks, whereas those who only preloaded once, or not at all, only lost an average of 0.8kg.
Parretti said, "When combined with brief instructions on how to increase your amount of physical activity and on a healthy diet, this seems to help people to achieve some extra weight loss, at a moderate and healthy rate. It is something that does not take much work to integrate into our busy everyday lives."
The study was published in Obesity.
Source-IANS