Compositions for affecting the intestinal microbiome of a mammalian subject can include a pharmaceutically-acceptable carrier and greater than or equal to 1×104 PFU/mL or PFU/mg of bacteriophage having a tropism that includes an obesogenic and/or inflammatory bacterium associated with an intestinal microbiome of a mammal. Processes for preparing the disclosed compositions can include isolating the bacteriophage from an environmental source, characterizing the bacteriophage, and combining the bacteriophage with the pharmaceutically acceptable carrier at greater than or equal to 1×104 PFU/mL or PFU/mg. Methods can include administering the disclosed compositions to a mammalian subject with or without co-administration of the disclosed probiotics. Administering the disclosed compositions can reduce a concentration of obesogenic and/or inflammatory bacteria in the intestinal microbiome of the mammalian subject, promote or induce weight loss, reduce inflammation, support metabolic health, and/or support a healthy balance/diversity within the intestinal microbiome of the mammalian subject.