Pedalwrench brings up an interesting point. Some energy drinks have a lot more calories than others. Hammer's products are especially calorie dense. You might take a look at this chart for a handy comparison:

http://www.trisports.com/drinks.html

One of the drinks listed--Spiz--strikes me as a bit too much. You body can only absorb so many grams of carbs per hour. Calorically, it packs a wallop, too, but if you're eating real food in addition to it, it sounds like a good way to gain weight while cycling.