Losing weight may be as simple as shrinking your dinner plate—and thereby reducing the portions you eat. According to the 9-inch “Diet” by Alex Bogusky and Chuck Porter (Powerhouse Books, $20), modern plates are 12 inches in diameter (compared with the 9-inch dishes of 1963), and diets often fail because our perception of portion size is inflated. One chapter is aptly titled, “Surprise, Your Eyes Really Are Bigger Than Your Stomach.” That’s (less) food for thought.