A University of California, San Diego School of Medicine study finds that weight loss programs that provide healthy fats, such as olive oil in the Mediterranean diet, or a low-fat, high-carbohydrate diet have similar impacts on pound-shedding. More specifically, the researchers report that a meal plan rich in walnuts, which are high in polyunsaturated fats, has a significant impact on lipid levels for women, especially those who are insulin-resistant.