What can cause a sour body odor?

Different things. I'd like more information. Is this an odor that's been persistent, or just appeared recently? Is this an odor that only you're aware of, or other people have noticed? Do you have any other medical diagnoses (such as diabetes)? Barring common issues such as hygiene or diet changes, some causes of a new sour odor include hormonal imbalance or possible infection.