I travel periodically for work and I usually take protein powder and a small hand blender along. I usually put the powder in a small tupperware-type tub and have never been asked about it at the airport. I've also always put it in my checked baggage and never tried to carry it on. Of course you can always try to use bars too. I've always taken them in my carry-on bag.
If you are going to be in a hotel for a few days, ask for a room with a refrigerator when you make reservations. Many also have small microwave ovens. Its easy to hit the local store or hotel breakfast bar for things like fruit, carrots, yogurt (I blend it in with the protein) or even microwaveable meals that aren't too detrimental to your eating habits.
Enjoy your vacation!
B-Mac