There has, apparently, been some research on this, but (IANADoctor) it doesn't look conclusive. https://pmc.ncbi.nlm.nih.gov/articles/PMC6330042/ https://pmc.n

There has, apparently, been some research on this, but (IANADoctor) it doesn't look conclusive. https://pmc.ncbi.nlm.nih.gov/articles/PMC6330042/ https://pmc.ncbi.nlm.nih.gov/articles/PMC6330042/ did mouse trials of fluoxetine and then checked the gut microbiome; they did find some changes in groups known to correlate with regulation of body mass. But, this is (a) mouse models and (b) a long string of correlations with (to my knowledge) no actual causal understanding.