If you're using fat-free dressing on your salad, you're doing it all wrong. According to scientists, you need to eat salad with fat-based dressings to get the most out of the veggies. Having no fat in your salad actually diminishes the benefit from eating vegetables.
This sounds a little crazy, right? Even though fat-free dressing has less calories than its fatty-filled counterpart, you're not getting the full oomph you want when eating vegetables with skinny dressings. Researchers at Purdue University compared eating salad with dressing that had saturated fat, monounsaturated fat and polyunsaturated fat at 3g, 8g and 20g of fat to find which was most effective, and they discovered that fat is a good thing. The Atlantic says:
Mario Ferruzzi, the lead author of the study and an associate professor of food science at Purdue, said that in order to get more from eating fruits and vegetables, they need to be paired correctly with fat-based dressings.
It turned out that dressing made with monounsaturated fat (olive and canola oil) were easily the most effective, needing the least amount of dressing to get the most amount of health-promoting carotenoids (carotenoids act as antioxidants in our bodies). Carotenoids are found in eating plant foods like vegetables and fruits, so it makes sense that we'd want to get as much bang as we can when eating them. Using salad dressing with fat accomplishes that. [Molecular Nutrition & Food Research via The Atlantic]