yeah, pig and chicken both have a lot of "large cyclic amino acids" tyrosine and phenylalanine. when a lot of this is dumped into the blood, it turns into dopamine, adrenalin, noradrenalin, and some other neurotransmitters which affect you in a similar way to stimulants, but in reverse. stimulants slow down or intensify the signalling from those neurotransmitters, where the food just increases the amount of them directly as they get synthesised into them.