Mixed

Obesity in older American adults is associated with a distinct gut microbiome taxonomic signature characterized by reduced species richness and specific shifts in bacterial abundance, including increased Bacilli (Streptococcaceae, Lactobacillaceae) and decreased Clostridia (Christensenellaceae, Clostridiaceae).

Your gut bacteria look different when you are obese, specifically with fewer diverse species and lower levels of certain beneficial bacteria like Christensenellaceae. While this doesn't tell you how to fix it directly, it suggests that restoring microbial diversity might be a valid area for dietary intervention, rather than focusing on simple 'good vs bad' bacteria ratios.