Beef gyros originated in Greece. They contain thin slices of meat — generally lamb or beef — mixed with vegetables such as tomato and red onion. Usually, a beef gyros is served in a warm pita bread. Gyros is a high-calorie food.

According to a recipe on the Food.com website, a portion of beef gyros contains 1/4-pound of beef steak, 1/2-clove of garlic, 1/4-teaspoon of oregano, 1 tsp. of olive oil, 1/4-ounce of feta cheese, one pita bread, 1/2 large plum tomato, a little red onion and 1 ounce of ranch dressing.

A quarter-pound of fried beef steak with the fat trimmed off contains 212 calories, according to the U.S. Department of Agriculture's MyFood-a-pedia calorie counter website. A piece of pita bread packs 124 calories. A teaspoon of olive oil is equal to 40 calories, while an ounce of ranch dressing has 142. A quarter-ounce of feta cheese has 99 calories and half a plum tomato 16. Half a clove of garlic equals 2 calories, while oregano and red onion total about 6 calories together.

A beef gyros in white pita bread contains around 639 calories by adding up these ingredients; the FatSecret website, meanwhile, calculates that one sandwich with similar ingredients weighs in at 587 calories. Changing the ingredients or cooking could raise or lower the calorie amount. For example, using whole-meal pita bread or low fat dressing would reduce the calories, as would roasting or grilling the beef instead of stir-frying it.