If a molecule can downregulate (downmodulate?) cravings so effectively, could there be a molecule that does the opposite?

This is basically about as far as I feel like entertaining conspiracy theories. I think it's a fairly grounded one, compared to most.

Not claiming that a molecule or a class of such molecules (or a perfect storm of unrelated molecules acting indirectly) is behind the obesity epidemic, or that there's explicit malicious intention involved, just that it does make me wonder.