Most pre-packaged salad dressings taste savory but are actually full of sugar or high fructose corn syrup. Just two tablespoons of some dressings contain more sugar than a donut. And the ones that don't use sugar? They're overloaded with fat. In some cases, two tablespoons will contain your entire daily recommended intake of fat. Many salad dressings also contain soybean oil, which has been known to increase appetite. When you're trying to be good by eating salad, this kind of defeats the purpose.
High fructose corn syrup goes one better and increases appetite while causing a number of serious health problems, such as diabetes and obesity. For a healthier alternative, make your own dressing with natural ingredients, such as olive oil, lemon juice, balsamic vinegar, and mustard. Even whole egg mayonnaise is a better alternative than using bottled salad dressings.