单选题 .  It's safe, it's simple, and it works: Drinking moderate amounts of water really can help you lose weight, new research shows.
    In what researchers claim is the first-ever randomized (随机的) trial of the effect of water consumption on weight loss, scientists from Virginia Tech found that dieters who started each meal with two 8-oz. glasses of water lost nearly five pounds more, on average, than dieters who did not, over the course of 12 weeks. There's no shortage of anecdotal (轶事的) evidence about how water might work to control your appetite. It fills you up so you don't eat so much; it quenches your thirst so that you don't turn to calorie-rich sodas or juices when your body just needs liquid. But until now, the researchers say, there has been no true evidence that water's appetite-suppressing benefits ever translate into actual weight loss.
    Now there is. In the 12-week study period, dieters instructed to drink water with every meal lost an average of 15.5 pounds; dieters given no instructions lost, on average, just 11 pounds. The research was presented at a national meeting of American Chemical Society.
    Perhaps the most surprising thing about the finding is how little we still know about healthy water consumption in general. In fact, although doctors and public-health authorities regularly remind us to drink more water, very few studies give any insight into what our ideal quantity may be. You know that conventional wisdom about eight glasses per day? Dartmouth professor Heinz Valtin investigated in 2002 and found no clinical evidence to support the advice. No one, it seemed, could prove that less (or more) water wouldn't be just as healthy.
    The new results today suggest that many Americans could indeed stand to drink a little more water than they do—especially if that water comes as a substitute for other high-calorie drinks. But you're looking to lose weight, be aware that it is actually possible to drink too much water, and you probably won't help matters any by drinking gallons (大量) at a time. In extreme cases, excessive water consumption can even be fatal, if it causes your blood concentration of sodium (钠)to fall too low. A couple of glasses with each meal, however, should be no problem at all for a healthy person.6.  The experiment done by scientists from Virginia Tech found that ______.