Key Findings: The authors identify six mechamisms that contribute to plant-based diets reducing body fat. All of these factores inrease satiety and energy expenditure, which reduces body weight: (1) reduced caloric density, (2) improved gut microbiota symbiosis, (3) increased insulin sensitivity, (4) reduced trimethylamine-N-oxide (TMAO), (5) activation of peroxisome proliferator-activated receptors (PPARs), and (6) over-expression of mitochondrial uncoupling proteins.