Certainly on the front end, one of the options would be to simply use jquery to do that work for you. A quick search revealed one method that would likely do the trick - you would surround the article body requiring a word count with a class of "to_count" and then use jquery with a bit of regex to detect and count the words within that class element. This assumes that you're OK loading jquery on the page in which you need the count.
Alternatively, you could instead use an EE add-on like MD Character Count to give you a word count within the control panel and then you could add a custom field in which to record that value (but this may incorrectly assume that the content requiring a total is contained within a single field).