Typically body odor is the result of natural oils in the pores mixing with bacteria which it comes in contact with. Sometimes people can experience an odor that smells similar to garlic when they are on a certain medications, though it usually does not indicate an underlying condition of any kind.
While garlic may be able to affect how your breath smells, it will usually not affect body odor whatsoever. Chances are if you are having problems with body odor that smells similar to garlic, it is a drug reaction taking place. Sometimes though if a person eats a very large quantity of garlic, it can seep through the pores and emit a smell which one could perceive as body odor.