Throughout my career, a common question that arises is whether water consumption before or during a meal really helps with weight loss. A common responses to this question is that people often confuse hunger for hydration, but a recent study may provide an answer to this question that is based on science. A randomized clinical trial published in the February edition of Obesity examined how water intake might affect weight loss in overweight and obese individuals age 55-75 (1). One group received a low-calorie diet with an emphasis on increased water consumption (water group: 16 fluid ounces of water prior to each of the three daily meals), and the other received a low-calorie diet alone (non-water group).
Neither group was aware of the true intention of the study prior to participating. There were no differences between the two groups at the start of the trial with regards to age, anthropometrics, blood chemistry or physical activity. Measurements were taken at baseline and at the end of 12 weeks. At the end of the trial both groups had lost a significant amount of weight, but those who had been instructed to consume 16 fluid ounces of water prior to each meal had a 44 percent greater weight loss than the non-water group. This equated to an approximate four-pound difference between the two groups. The mechanism through which water may be impacting weight is not fully understood, but it may be in part that it reduces energy intake at each meal and increases feelings of fullness.
- Dennis EA, Dengo AL, Comber DL, Flack KD, Savla J, Davy KP, Davy BM. Water consumption increases weight loss during a hypocaloric diet intervention in middle-aged and older adults. Obesity (Silver Spring). 2010 Feb;18(2):300-7.