I too have taken True Protein RTD's all over the world. Long-haul flights like Newark-Delhi, Atlanta-Dubai, Atlanta-Moscow, Chicago-Beijing and not once did I ever have a problem using them or with customs/immigration officials.
Only time I ever did have a problem was on a lousy little Continental flight from Houston to Fort Lauderdale where the bitch male flight attendant claimed they did not have enough bottled water on board to fill the tiny plastic bottle with a few ounces of H2O!
WORLDSPAN