Melissa
Check out digitexas reply on the TSA thread. If he can bring Boost and only needs to call over a supervisor, that should be the worse for you also for the Ensure. Since they are both supermarket drinks, TSA will probably treat them the same.
I began to wonder whether my prescription Jevity was not an accurate predictor but his post confirms my experiences.
Now don't be "taking the slide" off the plane like that flight attendant if they do give you a hard time

Charm