According to MAL , yeah . <| sep |> Walnuts inside their green husks are indeed as big as apples . Or better comparison since apples come in many sizes , as big as tennis balls . <| sep |> Broadly speaking , psych meds mess with serotonin and dopamine , along with a few other neurotransmitters . Those contribute to your appetite and sense of satisfaction with eating . As I understand it , more serotonin leads to less of an appetite , and a lot of meds for bipolar disorder and schizophrenia , among others , tend to lower serotonin meds for depression and anxiety tend to raise it . There ' s also the fact that serotonin naturally ebbs and flows throughout the day in response to stimuli like eating and other rewardmotivated behaviors , and some researchers think that psych meds interfere with that process by keeping serotonin on a more even keel great for psych disorders , bad for appetite . Lowering serotonin and dopamine also causes more fatigue more sitting around on the couch . Also , while I was googling around doublechecking my pharmacology I also came across this article it might be tough to parse if you don ' t have a science background , but the gist is that in mice , risperidone alters the gut bacteria , leading to a slower metabolism . All the mice were fed the same , but those treated with risperidone actually used energy more efficiently , resulting in more fat storage . Fascinating stuff , and it means that the answer may actually be a little of both , as opposed to purely appetiterelated like we used to think .