From Longman Dictionary of Contemporary Englishat gut levelat gut levelINSTINCTif you know something at gut level, you feel sure about it, though you could not give a reason for it She knew at gut level that he was guilty. → gut
Examples from the Corpus
at gut level• Intellectual conviction is nothing like feeling at gut level.• She knew at gut level that he was lying.• For one thing, this new record hits you straight at gut level the first time. 