A roast beef sandwich on white bread is a deli classic. Usually made with beef from the round, or hind leg, section of the cow -- roast beef is one of the leaner cuts of beef with fewer calories than fattier sections.
A roast beef sandwich made with 2 oz. of roast beef from the eye of round and two large slices of commercially prepared white bread contains 270 calories. Use smaller slices of bread and save just 22 calories.
Adding condiments to your sandwich may significantly affect the calorie count. Use mayonnaise and add 99 calories for each tbsp. Go for yellow mustard instead and take in just 3 calories per tsp. A tbsp. of horseradish is also low in calorie with just 7 calories per tbsp.
Increase the nutritional value of the sandwich without adding significant calories. Add a couple slices of tomato and fresh romaine lettuce leaves for a half serving of vegetables. Use whole wheat or rye bread to double the fiber content of the sandwich. One slice of these whole-grain breads also counts toward the 3 oz. minimum recommended by the U.S. Department of Agriculture.