Our bodies are about 60% water. We could not live without water. Our most ancient ancestors evolved in water, which may be why almost all life is dependent on it. A few species, like the land-dwelling ancestors of whales, were even pulled back into the water by evolutionary forces to become aquatic mammals.
But could this most ubiquitous, and essential of substances help with weight loss? It sounds crazy to ask, since, if the solution to being overweight were that simple, then why are so many of us fat?
A quick look at the scientific literature lead to an interesting study on children in: Int J Obes (Lond). 2011 Oct;35, by Dubnov-Raz G, Constantini NW, Yariv H, Nice S, Shapira N. – Influence of water drinking on resting energy expenditure in overweight children:
This study demonstrated an increase of up to 25% in REE following the drinking of 10 ml kg(-1) of cold water in overweight children, lasting for over 40 min. Consuming the recommended daily amount of water for children could result in an energy expenditure equivalent to an additional weight loss of about 1.2 kg per year. These findings reinforce the concept of water-induced REE elevation shown in adults, suggesting that water drinking could assist overweight children in weight loss or maintenance, and may warrant emphasis in dietary guidelines against the obesity epidemic.
This is remarkable. While the amount of weight loss would be modest, it was still statistically significant.
It looks like the potential weight loss was due to water raising their REE(Resting energy expenditure). What this also suggests is that one of the keys to losing weight or keeping it off is to maximize our REE. Obviously, this can be achieved through exercise, but it may be more important to not be inactive(sitting down for several hours) for extended periods of time, since this can negate the effects of regular exercise.
It must be noted that this was just one study; follow up studies on water could fail to replicate the findings of the first one, especially when you consider how the potential for weight loss was almost statistically insignificant. Also, this study was done on children, so the findings may not apply to adults, and the study concerned the potential for weight loss, not actual weight loss.
Still, it is a sound idea for the weight conscious to drink water instead of calorie containing drinks. So if you’re struggling to lose weight, among all the other things you are doing, fill yourself up with water before meals or if you are experiencing cravings.