If the body odor is extreme or chronic it may be a metabolic disorder.
According to Medline Plus:
"The hereditary disorder is called trimethylaminuria (TMAU), a disease that impairs the ability of an enzyme to metabolize or transform the compound trimethylamine (TMA). TMA is produced when we digest foods rich in a substance called choline -- including saltwater fish, eggs, liver and certain legumes, like soy and kidney beans."
Hope this helps some. Thank you for your question.