Given the 60 percent surge in the adrenal hormone noradrenaline within minutes of just drinking two cups of plain water, might one get the weight-loss benefits of noradrenaline-releasing drugs, like ephedra, without the risks? You don’t know until you put it to the test. Published in the Journal of the Endocrine Society, the results were described as “uniquely spectacular.” Drinking two cups of water increased the metabolic rate of men and women by 30 percent. The increase started within 10 minutes and reached a maximum within an hour. In the 90 minutes after drinking a single tall glass of water, the study subjects burned about an extra 25 calories. Do that four times throughout the day and you could wipe out 100 extra calories— more than ephedra! You’d trim off more calories drinking water than taking weight loss doses of the banned substance, ephedrine—the active component of ephedra—three times a day. And we’re just talking about plain, cheap, safe, and legal tap water!
Using the 10-Calorie Rule I explained previously, unless we somehow compensated by eating more or moving less, drinking that much water could make us lose 10 pounds over time. “In essence,” concluded one research team, “water drinking provides negative calories.”
A similar effect was found in overweight and obese children. Drinking about two cups of water led to a 25 percent increase in metabolic rate within 24 minutes, lasting at least 66 minutes until the experiment ended. So, just getting the recommended daily “adequate intake” of water—about 7 cups a day for children ages 4 through 8, and for ages 9 through 13, 8 cups a day for girls and 10 cups for boys—may offer more than just hydration benefits.
Not all research teams were able to replicate these findings, though. Others only found about a 10 to 20 percent increase, a 5 percent increase, or effectively none at all––pouring cold water, one might say, on the whole concept. What we care about, though, is weight loss. The proof is in the pudding. Let’s test the waters, shall we?
Some researchers suggest, “The increase in metabolic rate with water drinking could be systematically applied in the prevention of weight gain….” Talk about a safe, simple, side-effect-free solution—in fact free, in every sense. Drug companies may spend billions getting a new drug to market; surely a little could be spared to test something that, at the very least, couldn’t hurt. That’s the problem, though. Water is a “cost-free intervention.”
There are observational studies suggesting those who drink, for example, four or more cups of water a day appear to lose more weight, independent of confounding factors such as less soda or more exercise. But you don’t really know until you put it to the test.
And finally, in 2013, “Effect of ‘Water Induced Thermogenesis’ on Body Weight, Body Mass Index and Body Composition of Overweight Subjects.” Fifty overweight “girls” (actually women, ages 18 through 23) were asked to drink two cups of water, three times a day, a half hour before meals, over and above their regular water intake, without otherwise changing their diets or physical activity. And, they lost an average of three pounds in eight weeks. What happened to those in the control group? There was no control group, a fatal flaw for any weight loss study due to the “Hawthorne effect,” where just knowing you’re being watched and weighed may subtly affect people’s behavior. Of course, we’re just talking about water; so, with no downsides one might as well give it a try. But I’d feel more confident if there were some randomized, controlled trials to really put it to the test. Thankfully, there are!