Simple meals from McDonald’s — the hamburger, milkshake, and fries — were emblematic of widespread adoption of the meat-and-dairy-heavy “Standard American Diet.” The McDonald brothers built the modern drive-in restaurant, having customers stop their cars and give their orders through a kitchen window. This sped up service, but the McDonald brothers wanted even more efficiency. They hired consulting engineers from Environmental-Safety Consultants, a California firm that had invented wartime food distribution techniques, to redesign their kitchens for “quality, service, cleanliness, and value.”