- Protein bars are okay once in a while if you absolutely cannot find another source of food. Most protein bars really don't have that much protein in them and can be deceiving. Alot of them are loaded with hidden sugars and partially hydrogenated oils which means bad fat, so be careful and read the labels.

Mixing different brands of powders and bars doesn't make any difference, just be careful about whats actually in the bars and you should be fine. Keep in mind however the best source of protein is whole foods loaded with lean protein like chicken breasts and so forth. Maybe you could just bring prepared snacks to work? Or get some beef jerky or something.