Vinegar and baking soda are both good choices for removing body odor from clothes. Baking soda, in particular, makes a good soak while vinegar is a good regular additive to wash loads.
For extremely smelly clothes, soaking them in 2 cups baking soda added to a filled washer tub or sink for at least 24 hours prior to washing them is highly recommended. After the clothes have soaked, they can be washed as usual. Adding 1 cup of baking soda or distilled vinegar to the washing machine along with the regular detergent and washing as usual dispels mild odor. Vinegar and baking soda also help remove stains caused by excessive sweating.