The salad bar usually gives one healthy choices. Avoid the salad dressing, chopped ham, eggs and desserts. Go for the lettuce, raw onions, broccoli, cauliflower, fresh fruit, etc.
Some brands have zero calories actually meaning there are less than five calories per serving.
I had in a restaurant was in Chicago where I ordered steamed, chilled vegetables. First, they were steamed then chilled and the result was delicious. There was even enough to take with me to make another meal. If you want to eat in a healthy way at a restaurant you'll often have to ask questions. The way certain foods are prepared may surprise you.