Nothing loath is a phrase that essentially means to be very willing or eager to do something. There are a variety of different synonyms that could be used to convey this same sentiment, depending on the particular context in which the phrase is being used. Some possibilities might include phrases like "more than happy," "enthusiastic," or "eager as can be." Other potential synonyms might include phrases like "raring to go," "chomping at the bit," or "fired up and ready to roll." Ultimately, the best synonym will depend on the specific nuances and connotations of the original phrase and the overall tone and intention of the sentence or passage in which it appears.