If you're an adult U.S. citizen, chances are you're overweight. Indeed, there is almost a one-in-five chance that your body-mass index is greater than 30, which technically qualifies you as obese. Yet somehow, surveys say that at any given moment, almost 40 percent of the country's population is attempting a diet. Bon apptit!

The lipid-losing marketplace is growing even faster than the population's waistline. Weight loss is conservatively a $30 billion a year industry in the United States. Consequently, few industries are more competitive, more profitable, or more innovative. Can't summon the willpower to sustain a diet? Pop an appetite suppressant. Lack the patience to shed those unsightly pounds slowly? Consider liposuction. Still morbidly obese after failing diet after diet? A stomach reduction or stapling may be the surgical solution for you. The caloric continuum stretches from Diet Coke to nascent genomic techniques for reengineering the digestive tract.

What makes the weight loss enterprise so intriguing is just how cleverly it gets people to reframe the fundamental questions asked by anyone giving serious consideration to adopting an innovation. The most important question always asked, of course, is "Does it work?" But the question that will ultimately make or break the adoption is "Is it worth it?"

As any dieter or candidate for elective surgery knows, that question concerns issues of self-image and safety as much as personal finance. The ability to perform liposuction under local rather than general anesthesia has contributed enormously to the procedure's popularity. Medical reports that link many diet pills to irreversible organ damage, on the other hand, have reduced the appeal of such remedies.