Get yourself some chicken breasts, pork loin chops, skinned salmon fillets, basically some good quality lean meats. Pre-cook them. While they are cooking, wash and cut up some broccoli, onions, squash, zucchini, carrots, green beans, asparagus...basically just a bunch of fresh veggies.
Buy yourself some of these ziploc microwavable steam bags:
Put a pre-cooked chicken breast, pork chop, or salmon fillet in 5 of these bags and throw in an assortment or combo of your freshly chopped veggies in each bag and store them in your refrigerator. Now all you gotta do is take one out each day, take it to work, throw it in the microwave for about 4 minutes and enjoy a delicious "clean" lunch that is packed with a bunch of nutrients to help you build muscle and drop fat.
As long as you have a desk drawer, microwave, and refrigerator at work...you got everything you need to make healthy lunches and store healthy snacks like cheese, nuts, yogurt, jerky, fruit, veggies, and protein shakes.
This is what I do...and I've dropped roughly 20 pounds since January and all of my lifts have progressed throughout my 4 week workout programs. Best of all....I get to eat really delicious foods.