In a study of lab animals, Schugar et al. found that TMAO is associated with obesity and energy metabolism, antisense oligonucleotide-mediated knockdown or genetic deletion of the TMAO-producing enzyme FMO3 has a protective effect on the obesity of mice (Schugar et al., 2017). This evidence concerns the gene FMO3 and obesity due to melanocortin 4 receptor deficiency.