That's a gas... It wouldn't work for it wouldn't seep into my flesh.
How do you know that the government isn't just making up the idea of 'heart attacks' and really poisoning and killing fat people so that they can take out their fat and organs to be processed for rocket fuel and propane? After they killed the target, they would just stuff them with cotton and let their families bury them.
That being said, you could always...get fat.