A Pint of Water Before Meals May Speed Weight Loss

Dr Helen Parretti NIHR Clinical Lecturer University of BirminghamMedicalResearch.com Interview with:
Dr Helen Parretti
NIHR Clinical Lecturer
University of Birmingham

Medical Research: What is the background for this study?

Dr Parretti: Drinking water is widely advocated as a useful tool in weight loss and is included in many weight loss programs, yet there is little evidence to support this in practice. Some initial small laboratory studies suggested drinking water before main meals might help with weight loss, but we didn’t know whether it would work in an everyday setting over a sustained period of time.

Medical Research: What are the main findings?

Dr Parretti: We recruited 84 people into the trial. 41 in the “preloading water” group and 43 in the comparator group. The people in the preloading water group were asked to drink 500ml (around 1 pint or 2 glasses) of water 30 minutes before each main meal and lost, on average 1.3kg (2.87lb) more than those in the comparator group over 12 weeks. 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).

Medical Research: What should clinicians and patients take away from your report?

Dr Parretti: We believe that drinking 500ml of water before main meals is a simple message that could easily be given by healthcare professionals to patients with obesity when they are giving weight loss advice. When combined with brief instructions on how to increase your amount of physical activity and on a healthy diet, it seems to help people to achieve some extra weight loss – at a moderate and healthy rate.

Just drinking about a pint of water, three times a day, before your main meals may help reduce your weight and it’s something that doesn’t take much work to integrate into our busy everyday lives

Medical Research: What recommendations do you have for future research as a result of this study?

Dr Parretti: We would like to carry out a larger trial with 12 month follow up to allow us to gain more definitive evidence that water preloading is effective and also to investigate the potential mechanisms of action more fully.  We are now looking to gain funding to carry out this research.


Helen M. Parretti, Paul Aveyard, Andrew Blannin, Susan J. Clifford, Sarah J. Coleman, Andrea Roalfe, Amanda J. Daley. Efficacy of water preloading before main meals as a strategy for weight loss in primary care patients with obesity: RCT. Obesity, 2015; DOI: 10.1002/oby.21167

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MedicalResearch.com Interview with:, & Dr Helen Parretti (2015). A Pint of Water Before Meals May Speed Weight Loss 

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