The results of the small study need to be confirmed in bigger trials, though, say the researchers from the University of Birmingham in the U.K.
The study team recruited 84 obese adult volunteers through their doctors.
Everyone received a weight-management consultation that covered lifestyle changes, better diet choices, and the benefits of more exercise.
Then the researchers randomly split the participants into two groups. They asked one group of 41 volunteers to drink 500 milliliters (about 16 ounces) of water half an hour before meals. Sparkling water, carbonated drinks, or sweetened drinks were not allowed.
The other 43 participants were just advised to imagine they were full before eating.
After being tracked for 12 weeks, with a phone consultation after 2 weeks, the water-before-meals group lost an average of 2.87 pounds more than those who just imagined being full.
People who loaded up on water before all three main meals a day lost an average of 9.48 pounds. Doing that just once a day, or not at all, resulted in an average loss of 1.76 pounds.
The findings are published in the journal Obesity.
"The beauty of these findings is in the simplicity. Just drinking a pint of water, three times a day, before your main meals may help reduce your weight," says Dr. Helen Parretti, one of the study authors, in a statement. "When combined with brief instructions on how to increase your amount of physical activity and [get] on a healthy diet, this seems to help people to achieve some extra weight loss -- at a moderate and healthy rate. It’s something that doesn't take much work to integrate into our busy everyday lives."
The study team now wants to carry on the research in a bigger trial with more volunteers.