First, Bring your own snack (BYOS)! Along with your underwear and tooth brush, pack a few snacks. This will provide you relief if you find yourself hungry with limited options and it will stear you away from the cookies or chips which so conveniently find their way on most trips.
Second, make the better choice. Whether traveling by auto or airplane, you will likely have a variety of options available to you. Sure they may not serve your egg white omelet with low fat cheese, peppers, and onions for breakfast but when given the option of bagel or muffin, which do you choose? One of the biggest mistakes people make when it comes to healthy eating is that because they cannot have the best choice they justify making the worst choice. Always remember to take the better option and limit the portion. If you focus on the best of the options available, you will have much greater success in achieving your best health.
Finally, walk it off. Whether you have a busy business trip or a relaxing family vacation, find ways to get extra steps in your day. I have found myself many a times in the Detroit airport on a 45 minute layover walking terminal C from one end to the other and back again. Even if I am traveling by myself, the extra luggage only adds resistance and strength training.
Do the best with what is available to you. Get creative and you will find that traveling is great for your health!