A 2014 Harvard University study in Nature found that a fully meat-based diet did not change alpha diversity in the human gut microbiome.

“this one is from Harvard University interestingly and they gave patients a fully meat-based diet compared to a plant-based diet title of this study diet rapidly and reproducibly Alters the human gut microbiome this is from nature 2014 what they found in this study was that the alpha diversity did not change at all when patients had zero plant fiber in fact the alpha diversity which you can see at the end of this paper was about the same in both of the studies though the beta diversity improved or increased on a carnivore diet they say no significant difference is in Alpha diversity were detect on either diet which means that when they gave more plant fiber to these study participants there was no increase in Alpha diversity and when they decreased plant fiber significantly there was no there was no decrease”