Water Consumption and Body Weight

by on January 11, 2015

in Monthly

Drinking more water is considered a healthy habit and many families have made that one of their goals for the New Year. Dietary guidelines from Canada, the USA and Germany all suggest that water be the preferred beverage to fulfil daily fluid requirements, but is there research data to back that up, even if it seems to be common sense? (It has been said that when one’s pants are on fire there is no need to do research to find that the solution may be to pour a bucket of water on the flaming pants.)

Water intake—as opposed to sugar sweetened beverages (SSB), soft drinks and drinks with artificial sweeteners—is socially desirable and assumed to be the ideal. It makes a lot of sense that when we reduce our energy intake by reducing sugar intake we should lose weight; that when we have a glass of water before a meal, we will reduce our appetite; that when we drink cold water our bodies have to increase the resting metabolic rate at least temporarily and that our hydration status determines our appetite.
Ideally any recommendations by public health agencies should be based on rigorous research —thus, a fair question may be to consider all the published research which pertains to water intake and weight management.

The Berlin School of Public Health did exactly that. In a comprehensive review of how water consumption impacts body weight in humans between the ages of two and nineteen years, the author’s conclusion may not be what most of us would have expected.
The Berlin study, published in the December 2014 edition of the journal Obesity, is the very first ever pediatric study to comprehensively look at all the previous studies of how water impacts children’s body weight.

The review of current electronic databases such as MEDLINE and Cochrane reviews enabled the authors to conclude that specifically in children, cross-sectional studies show that higher water consumption is associated with a higher weight status. It is speculated that when obese children consume foods high in salt, they tend to drink more water. The bottom line is that longitudinal studies, all done only in children, suggest a weight reducing effect of water consumption, but evidence for a causal association is still far too low.

The Berlin paper, a landmark study, but sure to draw an avalanche of criticism, reminds us that the evidence of water-drinking preventing obesity is still limited– even though it may appear to be logical that drinking more water will lead to weight loss. It does not mean that we should not try to consume more water, but based on reviewing numerous rigorous scientific studies it appears that the benefits of water-consumption in reducing obesity may have been over-stated.

This study also reminds us to carefully consider the evidence and science supporting socially desirable interventions.
Interventions which may seem to be politically correct, such such as taxing so called junk-foods or manipulating the food environment of families should not be enforced unless there is solid science to support that.

In the same journal (Obesity Dec 2014), the Obesity Society and the American Society of Nutrition jointly sponsored a series of reviews on the current state of understanding on issues such as: food prices and obesity; the role of targeted food taxes and subsidies; food availability/convenience and obesity; and the role of frequent but smaller meals for body weight management.
These reviews were done by authors considered experts in the field of food environments and its impact on obesity. These reviews were published in Advances in Nutrition 2014, volume 5. The common thread —similar to the Berlin paper—once again is that we need more robust research before we can make definitive recommendations.

In other words, applying this science in Canada, if Health Canada or a Senate committee on the issue of obesity prevention were to make recommendations, the bigger question should always be, “Where is the comprehensive scientific data to back it up?” Advocacy for the health of children should be admired but unless it is based on solid science such advocacy may be seen by some as enforcing a nanny-state by an over-reaching government.

In the end, the whole matter of weight loss and the maintenance of that loss come down to studying patients who were successful. Results speak louder than scientific speculation and public health authorities’ recommendations. For that reason I am attracted to, and impressed by, the National Weight Control Registry, an organization which tracks the habits of patients who lost 10% of their body weight and kept it off over the long-term. For more information how patients did that, see www.nwcr.ws
Meanwhile do not give up on drinking more water and if you find it impossible to avoid fruit juices, at least dilute them by adding water—this will reduce the sugar load and “soften” the blow. Sparkling water used to dilute fruit juices may be another option.

Comments on this entry are closed.

Previous post:

Next post: