Granted. However, as it turns out, this cheeseburger is in fact such a magnificent cheeseburger that it is the standard towards which all cheeseburgers naturally aspire - the Platonic Form of Cheeseburger-dom. It is literally perfect in every way, and as such cannot harm you should you consume it, nor will it ever rot or decay. As it is perfect, it also will not cause any negative effects on the world at large due to its existence, nor will it harm your weight.
However, this cheeseburger is simply too perfect to be eaten. While the burger itself does not harm the world, and, in fact, by its mere existence makes the world a better place, this is exactly the problem. Were you to actually eat it, you would knowingly be harming the world, something which you cannot do given the parameters of your wish. As such, you are left with the one true cheeseburger within your grasp, but are forever unable to partake of its deliciousness.
I wish that my hair was approximately 2% fluffier.
