As you may already know, the requirements have loosened regarding liquids/gels you can now take on your carry-ons when flying.
For all the details you can check the TSA site, but I just wanted to pass this info on re. RTD's.
I called TSA because I'm flying to Detroit this Saturday, 10/28. Turns out that you can bring RTDs in your carry-on if you get a note on official hospital stationery from your doctor stating that you are a Type II diabetic and need the liquid meals to help you maintain your blood glucose levels while traveling.
Only other thing you have to do is keep the RTD's separate from the rest of the contents of your carry-on and present both it and the note from your doctor to the TSA worker at Security for approval.
Don't know if it works the same if you're not a diabetic. Maybe if you can get your doctor to write that you are on a "restricted caloriic intake" plan and due to limited food choices at airports and on the plane need to have access to a liquid meal supplement it would also work.
I know it's a bit of a hassle, but for me, at least I'm going to be either at the airport or on the plane over a 10 hour stretch on Saturday, with a very short window of opportunity between flights to make and bolt down a packaged medifast meal. It just is a less stressful situation if I can merely pull out an RTD and drink it on the plane.
Hope this helps anyone planning on air travel in the near future.
Carmel