Begin by telling them, "The fat you eat is the fat you wear," and remind them that there is nothing attractive about wearing olive, flaxseed, or corn fat.  For this reason alone, most of your friends and family should steer clear of so-called "healthy oils" derived from plant-foods.  Gaining weight can be expected from consuming high-fat whole foods, such as nuts, seeds, avocados and olives, as well as "free oils," which are usually purchased in bottles. However, the shared propensity for weight gain is where the similarity between unprocessed plant foods and free oils ends.