Researchers from the University of Birmingham have shown that drinking 500ml of water at half an hour before eating main meals may help obese adults to lose weight. They believe that the simple intervention could be hugely beneficial, and be easily promoted by healthcare professionals and through public health campaigns.
Obese adult participants were recruited from general practices and monitored over a 12 week period.
Each of the participants, all adults with obesity, were given a weight management consultation, where they were advised on how to adapt their lifestyle and improve their diet and levels of physical activity. 41 of those recruited were asked to preload with water, and 43 were advised to imagine that they had a full stomach before eating.
Those in the group who were instructed to 'preload' with water lost, on average, 1.3kg (2.87lbs) more than those in the control group.
Those who reported preloading before all three main meals in the day reported a loss of 4.3kg (9.48lbs) over the 12 weeks, whereas those who only preloaded once, or not at all, only lost an average of 0.8kg (1.76lbs).
Dr Helen Parretti, NIHR Clinical Lecturer at the University of Birmingham, explained, "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."
"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's something that doesn't take much work to integrate into our busy everyday lives."
Participants were encouraged to drink tap water. Sparkling water, sodas or sweetened drinks were not allowed as part of the study.
The study, published in the journal Obesity, showed encouraging initial results for the trial, and the team hope that the findings will inform further research into the benefits of water preloading before meals. They hope to receive backing for a trial with a larger number of participants and over a longer period of time in order to confirm the findings.
Dr Parretti added, "Losing a few extra pounds over the course of a year can be significant to an individual, and this could be an easy way to help with that weight loss. It's a simple message that has the potential to make a real contribution to public health."