There are a few different reasons that a person has cellulite. Fat loss will help, but there is also a genetic component and age that may be out of your control
Basically your body loses collegen fibers with age...but there is no link between actually consuming collegen (like in the jello or blueberry drink) and having it effect the skin whatsoever. So drink it if you want to and like the taste but realistically know it may have little to no effect. Coincidentally, applying collegen via those magical skin creams do not penetrate the skin either. Seems the best way to treat cellulite is prevention!