White Castle opened in 1916 as the first fast food restaurant, focusing on hamburgers. McDonald's revolutionized the industry in 1948 with assembly-line production of fast food at high speed and low cost. Studies show that a fast food diet can negatively impact health, as shown in the documentary "Supersize Me" where the subject gained weight and his health declined after a month of eating only fast food. While fast food is inexpensive and tasty, the long-term health effects are more serious. Home cooking with fresh ingredients provides more nutritional and lower-calorie meals than fast food, though it may take more time to prepare.