Accounting for one out of every twenty consumer-dollars spent in America, the diet industry is booming like never before. There are water diets, low-fat diets, high-fat diets, low-carb diets, high-fiber diets, color-coded diets and fixed-menu diets. There are over-the-counter "fat burners" and prescription diet pills of every description and, lord knows, no end of gadgets, gimmicks and pseudoscientific mumbo jumbo designed to separate you from your...