Water Intake and Obesity
SUPER BRIEF SUMMARY
It is a long held belief (and common recommendation amongst providers) that EVERYBODY needs to drink more water. Even if you think you drink a lot of water every day, you still need MORE. Or at least, that’s what you may often hear. That being said, the actual data for this isn’t that strong.
Now, there is definitely some population level evidence out there demonstrating correlations between water consumption and improved diets and decreased caloric intake.³ This is then correlated to decreased obesity risk. However, the majority of the effect seems to come from the relative change of REPLACING sugar sweetened beverages (SSBs) with water. Though there does seem to be signal for sustained weight loss if drinking greater than 1 liter (about 34 ounces) of water a day independent of other factors, this effect is small and of questionable clinical significance¹.
So yes, replacing SSBs with water will likely help with your weight loss goals. However, just increasing water consumption ON ITS OWN does not appear to be the panacea we may want it to be, though drinking a large glass of water prior to a meal does seem to help with total energy intake.
THE WHOLE TALK
I think I get asked on an almost daily basis, “How much water do I need to drink?” My default response is almost always, “Well, it depends!”
I love using that answer.
But, it truly does depend. There are many variables that come into play:
activity level
body mass and biometrics
other medical conditions and medications
the ambient temperature you are in
what your specific goal is
etc, etc, etc
So I quite honestly can’t give a specific quantity of water to drink. However, is this talk we are going to discuss water intake and how it relates to weight loss and obesity. Here we go!
It seems to be a widely held belief that increasing water intake is a vital strategy to help improve weight loss and dieting success. Superficially, this seems to make general physiologic sense, but surprisingly there has not been a large body of data demonstrating this relationship. Large epidemiologic data demonstrated those that drink more water have a decreased total daily energy intake.³ Think, drink more water = eat fewer calories. But, the question is, is this related to the water itself or are people who drink more water also the same people that have healthier lifestyle habits at baseline.
Furthermore, it is also likely that increased water consumption is also correlated to decreased intake of sugar sweetened beverages (SSBs). SSBs are the bane of public health and the obesity epidemic. When I see a soda I see diabetes and obesity in a bottle. However, the majority of the effect seems to come from the relative change of REPLACING sugar sweetened beverages (SSBs) with water. Though there does seem to be signal for sustained weight loss if drinking greater than 1 liter (about 34 ounces) of water a day independent of other factors, this effect is small and of questionable statistical significance¹.
Another frequently discussed method is to drink a large glass of water before a meal. Theoretically, this can help with satiation (the feeling of fullness while eating a meal that signals to stop eating). According to research by Dennis et al, “when combined with a hypocaloric diet, consuming 500 ml water prior to each main meal leads to greater weight loss than a hypocaloric diet alone in middle-aged and older adults. This may be due in part to an acute reduction in meal <Energy Intake> following water ingestion.”²
However, in another study that compared premeal intake of 5 different beverages there was no difference in energy intake during the meal between the non-caloric (water) and the no drink groups. However, the caloric beverage groups (soda, juice, milk) did have a total increase in energy intake. This study was in a different population and only 44 participants, but this would seem to suggest the important factor is avoiding caloric beverages during a meal. According to the authors, “Subjects' ratings of fullness after lunch did not differ among the beverage conditions, but were lower for the no-beverage condition. These results show that when caloric beverages are consumed with a meal they add to energy intake from food, without significantly affecting satiety ratings.”⁴
So, where does this leave us? It does indeed seem that relative increased water consumption is related to decreased daily energy intake. Though, the majority of the effect appears to be related to decreased intake of SSBs. However, it remains to be seen if the average daily water intake ITSELF is the cause or just related to healthy lifestyle habits at baseline. That being said, there were several studies I found that demonstrated decreased energy intake and increased satiation during a meal when non-caloric beverages were consumed prior to the meal. Given there is no real harm to increasing water consumption in most patients I will likely recommend this strategy to my patients looking for other tools to help in their weight loss journey.
Thanks for reading!
SOURCES
Stookey, Jodi D., Florence Constant, Barry M. Popkin, and Christopher D. Gardner. “Drinking Water Is Associated With Weight Loss in Overweight Dieting Women Independent of Diet and Activity.” Obesity 16, no. 11 (2008): 2481–88. https://doi.org/10.1038/oby.2008.409.
Dennis, Elizabeth A., Ana Laura Dengo, Dana L. Comber, Kyle D. Flack, Jyoti Savla, Kevin P. Davy, and Brenda M. Davy. “Water Consumption Increases Weight Loss During a Hypocaloric Diet Intervention in Middle-Aged and Older Adults.” Obesity 18, no. 2 (2010): 300–307. https://doi.org/10.1038/oby.2009.235.
Popkin BM, Barclay DV, Nielsen SJ. Water and food consumption patterns of U.S. adults from 1999 to 2001. Obes Res 2005;13:2146–2152.
DellaValle DM, Roe LS, Rolls BJ. Does the consumption of caloric and non-caloric beverages with a meal affect energy intake? Appetite 2005;44: 187–193.
