Before you hit the salad bar, see how some popular ingredients compare.

WINNER: Balsamic vinaigrette. Balsamic vinaigrette can contain a third fewer calories and grams of fat than Italian dressing. Bottled versions of both are often made with additives and preservatives, so mix your own: Combine three parts olive oil with one part balsamic vinegar and a little salt and pepper.

WINNER: Spinach. It's a close call — both are super low in calories and packed with nutrients. Spinach contains slightly more phytonutrients, antioxidants, B vitamins, potassium, calcium and iron. Spring mix usually contains spinach, but it's bulked up with lighter lettuces like frisee that don't offer much in terms of nutrition.

WINNER: Feta. Cheddar has 32 percent more protein and 49 percent less sodium than feta. But feta has fewer calories and grams of fat (total and saturated) than cheddar and because it's so creamy and flavorful, a little goes a long way.

WINNER: Grilled chicken breast. Sodium is the big issue here: Diced turkey is more likely to be processed and loaded with sodium — up to 16 times the amount in store-bought or restaurant-cooked chicken breasts. Also, chicken breast is white meat, while diced turkey can contain a mix of light and fattier dark meat.

WINNER: Croutons. Croutons are usually much lower in fat because they're sauteed or baked rather than deep-fried like tortilla strips. The exception? If you see croutons labeled "cheesy" (as opposed to plain), beware: The added cheese makes them almost as fatty as tortilla strips.

Food Network Magazine's expert Jaclyn London is a registered dietitian in New York City.