Talking on a cell phone may be considered rude in most restaurants, but tapping on a handheld device is perfectly acceptable -- encouraged, even, by people watching their weight.

Handheld devices do much more these days than keep schedules and store phone numbers. Many people trying to slim down use their handhelds or PDAs to track the food they eat and the exercise they perform. The biggest names in weight-loss are offering mobile versions of their plans that people can take with them wherever they go.

"We like to think of our new mobile product as a global positioning system for weight management," said Scott Parlee, director of product development for WeightWatchers.com. "Our customers told us they want tools to help them stay on course when they're at a restaurant, the grocery store, or the gym, so we found a way to put our weight-loss tools in the palm of your hand."

Weight Watchers(R) On-the-Go(TM) for handheld devices works in conjunction with a WeightWatchers.com account. You can follow Weight Watchers online and add the mobile product to the cost of your monthly subscription.

Followers of Weight Watchers track POINTS(R) values for food and activity, or follow a no counting plan in which they eat from a core food list until satisfied. The mobile product delivers food lists -- over 25,000 food items, including brand name groceries and menu items from national restaurant chains -- a tracker to keep tabs on food and exercise, and a POINTS calculator to help subscribers make smart meal choices anytime, anywhere. Unlike other mobile weight-loss products, Weight Watchers On-the-Go synchronizes entries between the handheld and a Web-based account, so that ham on rye eaten at lunch gets entered only once.

Myra Slepoy from New York attributes much of her weight-loss success to using her handheld. "I'm always running around and I use my PDA, so this is great for me. I can keep track of what I eat and how much I exercise. I can pull up food lists. I can go to a restaurant and pull up food that they have at that restaurant."

"Having the food lists in front of you takes the guesswork out of dieting and gives people a feeling of control," Parlee said. "Our customer surveys showed more and more people wanted wireless weight-loss tools. In fact, 30% of our subscribers use handhelds. They told us that they see it as a solution to stay on track, wherever they are."

Weight Watchers On-the-Go is compatible with most Palm OS-based handhelds purchased in the last few years from manufacturers such as Handspring, Palm and Sony. For more information, visit http://www.weightwatchers.com/