Over the years, we’ve often recommended the simplest of behaviour changes to improve your health: drinking more water during the day. There’s certainly no downside to staying hydrated, plus the increased trips to the bathroom will ensure you get up from your desk a few more times every day. I probably don’t have to convince you any more of the dangers of sitting for prolonged periods – Travis has done a fine job of that. But what if there was more behind the advice to drink more water? What if something as simple as a few more glasses of water resulted in weight loss?
A new study, published in the September issue of the journal Obesity suggests water can be an effective tool to combat excess weight, albeit modestly.
In the study, Parretti and colleagues randomized 84 adults with obesity to one of two basic conditions: 1) drinking 500 ml of water 30 min before their main meals or 2) a control group where participants were supposed to visualize being full before having their meals.
At the start of the study, all participants were given a 30 minute face-to-face weight management consultation and a 10 minute follow-up telephone consultation at 2 weeks.
41 participants were randomized to the intervention group and 43 to the control group, and their weight was tracked until the 12 week conclusion of the study.
And what effect could something as subtle as drinking water before meals have on one’s body weight?
At 12-weeks, participants who “preloaded” with water reduced their body weight by 1.3 kg more than participants in the control group.
Just to be sure, the authors performed another analysis where they adjusted for potential differences in the two study groups, such as ethnicity , age, and gender; this analysis confirmed significantly greater weight loss at 12 weeks among those who drank water before their meals..
Is this surprising?
Well, you may recall a somewhat similar prior study we discussed on this blog back in 2009 that randomized overweight/obese older men and women to either a hypocaloric diet alone or a hypocaloric diet plus increased water consumption for a duration of 12 weeks.
The hypocaloric diet consisted of 1200 calories for the women and 1500 calories for the men. Those in the diet + increased water group were required to consume 500 ml of water (2 cups) 30 minutes prior to each of the 3 large daily meals (breakfast, lunch, dinner).
While participants in both groups lost a significant amount of weight (5-8kg) in response to the diet, those who also consumed more water before their meals lost an additional 2 kg in comparison to the diet only group.
The greater weight loss in the group consuming pre-meal water could be the result of smaller caloric intake during each meal (~40 calories less per meal), as shown during the baseline laboratory test meals.
The findings of these randomized controlled studies are in agreement with prior epidemiological studies showing that caloric intake in water drinkers is on average 200 calories less than among non water drinkers.
The results provide compelling evidence to encourage all those attempting to lose weight to increase their daily intake of water to help in their efforts. Specifically, one should consume approximately 2 cups of water, about half an hour prior to most meals.
Reference: Parretti et al. 2015. Efficacy of water preloading before main meals as a strategy for weight loss in primary care patients with obesity: RCT. 2015; 23(9): 1785-1791.