For anyone who’s ever adopted a new diet plan for weight loss or overall health, it’s a familiar nightmare. The backdrop varies (an all you can eat buffet, holiday party, dark and silent kitchen in the middle of the night), but the suspense is universal. The temptation, a mental struggle, the cautious scanning of the room. A subliminal background track climbs in crescendo. You give into the slightest slip, a minor indiscretion, really, and suddenly there you are, dropping through a trap door, plummeting down a dark, cavernous shoot, screaming in terror, only to fall into a sorry heap of shame at the fiery center of the earth (or other subconscious setting for doom or disgrace).