Drink More Water, Lose More Weight?
Drink more water, Michelle Obama told us in the Let’s Move! campaign. She wasn’t the first with that advice. It’s everywhere. The presumption is that water can substitute for sweetened beverages, fill you up, and help you lose or maintain a lower weight. Thankfully, Julia Wong and colleagues from Boston Children’s Hospital tested that advice. They found no effect on weight in a small study of teens.
This was a good study, even if it’s not the final word on this question. It was randomized and controlled. Half of a group of 38 teens with excess weight and obesity were coached to drink 8 cups of water per day as part of a six-month weight management program. The other half participated in the weight management program, but received no advice to drink more water. Before the study started, these kids were drinking about two cups of water daily.
The kids in the test group didn’t reach the goal of drinking eight cups a day. But they more than doubled the amount of water they were drinking. The average was just shy of five cups a day. Even the kids who weren’t told to drink more water drank more. But they only reached 3.5 cups a day, significantly less than than the test group.
And in case you wondered, the researchers took urine samples for another indicator of how much water these kids were drinking. Those findings were generally consistent with the self-reports. (Of course, self-reports are far from perfect.)
So where do we go from here?
First of all, this doesn’t mean that the advice to drink more water is totally bogus. It’s a small study. But it does suggest that we can’t count on drinking more water to have a huge impact on weight management in teens.
Second, it’s pretty clear that getting these teens to drink eight glasses of water a day is a pretty tall order. None of them did it. True, these kids were chosen for the study because they were drinking less than four cups daily. But there’s no evidence that eight cups a day is the right goal.
So, the best advice might be to keep on drinking plenty of water. Hydration is good. But the best policy might be to look for more effective strategies to reduce obesity.
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March 11, 2017