graphic: phys.com

Sales of diet books, videos, and audio cassettes increased by 50 percent between 1991 and 1994.

THE diet business is fat and healthy. Anyone who swigs diet soda, works out regularly or subsists on fat-free food, is feeding this multi-billion dollar industry.

Annual diet industry revenues have grown from an estimated $100 million in the 1950s to $50 billion in the 1990s.

The industry encompasses all products and services that claim to change the body, including diet plans and products, exercise equipment and gyms. It has grown exponentially over the past four decades and shows no signs of ebbing.

Weight Watchers, the industry leader, estimates that it will make $85 million in 1999. It is the fastest growing division of Heinz, its parent company.

Profits have declined sharply in the past year for another leading diet company, Jenny Craig. The company took in only $2.1 million in 1998, down from $11 million the previous year.