Americans spend $40 billion a year on books, products, and programs designed to do one thing: help us lose weight. From Atkins to Ornish and Weight Watchers to South Beach, today's dieters have a dizzying array of weight loss programs from which to choose -- yet the underlying principles of these diets are often contradictory.

In "Diet Wars," FRONTLINE examines the great diet debate. Viewers follow FRONTLINE correspondent Steve Talbot, whose discovery that those "few extra pounds" have put him perilously close to the clinical definition of obesity prompts him to evaluate the myriad diets now available to overweight Americans.