After collecting eight years of data, Sharon P. Fowler, MPH, and colleagues at the University of Texas Health Science Center at San Antonio reported that diet soft drinks may do more harm than good. Fowler discovered that the overweight risk soars 41 percent with each daily can of diet soft drink. That isn't to say that diet sodas and such actually cause obesity, but they may be a contributing factor.
There are some theories behind why diet sodas may trigger weight gain. First and foremost is the human factor. Many times people drinking diet sodas believe they can get away with eating higher calorie foods because of all the calories they "save" by drinking diet sodas. There are actually those who regularly order high calorie fast food and then round out the meal with a diet soda. Some wonder, "what's the point?" While beverages do contribute to overall caloric intake, the drinking of diet soda does not negate the amount of fat and calories that a poor food choice would bring to the table. The result may actually be over-indulgence.
There is another factor in the diet soda/obesity connection. The body may actually be smarter than one gives it credit for. Upon drinking a sweetened diet beverage the body tastes the sweetness and thinks there are calories that will be coming with it. When there are no such calories, the body becomes confused and actually starts to crave even more calories to overcompensate.
Fowler offers proof to this idea. In a recent study, the feeding of artificial sweeteners to rat pups made them crave more calories than animals fed real sugar. So it stands that diet sodas with artificial sweeteners may actually boost appetite and make a person crave foods that aren't quite healthy. The better idea for individuals is to just consume a sugared beverage, or better yet, opt for a tall glass of water instead.