The surprise here? The vinegar that comes along for the ride in salad dressing also helps you feel full. Research has shown that vinegar can lessen the glycemic effect of a meal (meaning it tends not to spike your blood sugar), which has been linked to satiety that reduces food intake. Vinegar may also prevent body-fat accumulation, according to a 2009 animal study by Japanese researchers. Mice that were fed acetic acid, the main component of vinegar, for six weeks accumulated less body fat.