Dr. Barry Sears is a leading authority in the field of drug delivery systems and dietary control of hormonal response. The widespread understanding of the revolutionary impact of Dr. Sears? work in dietary control of hormonal response began with the publication of his landmark best-selling book, The Zone. The popularity of The Zone has led to the publishing of follow-up books such as Mastering the Zone and The Anti-Aging Zone. To date, more than three million hardcover copies of Zone books have been sold in the United States alone.