Will it be possible in the future that you will get an obesity vaccine in the same way that you get vaccinated for small pox of mumps? Maybe although for now it would help if you were a lab rat according to this story:

US researchers have developed a vaccine which prevents weight gain in rats, offering clues about human treatments.
The vaccine prompts the body to produce antibodies against ghrelin, a hormone that stimulates hunger and weight gain.

Vaccinated rats put on less weight while eating the same amount as those which did not have the jab.

A UK obesity expert said the Proceedings of the National Academy of Sciences study was interesting, but it might not be safe for people.