The linked page doesn't say the microbiome influences metabolism, only that it is suspected to be involved in digestion and fat absorption. Metabolism doesn't

The linked page doesn't say the microbiome influences metabolism, only that it is suspected to be involved in digestion and fat absorption. Metabolism doesn't happen in the gut, but in the cells and mostly in the mitochondria. It is controlled by the hypothalamus, which keeps your body at the same temperature, as this is the bulk of what food energy is used for.