First choice is to eat real food.
- bring a jar of coconut oil
- chicken or ceasar salad
- fast food burger no bread
Make you own bar
Ultimate Protein Bar - Perfect Macro-Nutrient Balance | Mark's Daily Apple Health and Fitness Forum page
Quest Protein bar Quest Low Carb Gluten Free Protein Bars - Official Site
Open your mind and take a look a paleo/primal. Eat the way humans have eaten for 100,000 years, not the 10,000 year old agriculture diet, or the 60 year old low fat diet.