Drugs hijack the reward system of the brain in a way that floods the synapses with a super intense signal. In response, the post-synaptic neurons will decrease the number of receptors for that signal. This creates a situation where more signal is needed to create the same high (i.e. tolerance) and a normal amount of signal leads to nasty effects (i.e. withdrawal).
So ‘what does this have to do with my weight?’ you might ask. Continue reading