Order what you want. You don't need to justify it. If someone gives you grief, just tell them that that's all you want. You don't "feel like" having any of the sides, just the meat. Repeat if necessary. It's the truth. It's like a similar strategy to avoid having friends press you to have "just a little" dessert. "I made it myself." "Come on. You have to try the [fill in the name of any carb-laden sugar bomb]. It's their specialty!" Just reply, "I don't feel like dessert." or "I'm full." or "I'm not hungry." Repeat until they stop. Very effective.