I know I'm going to be the spoilsport here, but here it goes:
Eat whatever the hell you want, but use the dang fitness center in the hotel!
Kung-Pao shrimp at PF Changs, a steak at the Outback or a big-ass Quizno's sub can all be fixed by a trip to the gym. Bonus: you feel good and have more energy for the day!
Blasphemy, I know. But I'd rather do beer, steaks and a workout than carry Nutrisystem crap with me.
Or you could do both - eat your home-packed tuna while doing pushups in your room. Soon you too can be ready for FIGHT CLUB!