If you've ever enjoyed a garlicky meal, you may have followed it with a quick breath check by cupping your hands to your face and huffing. At times like this, a personal stink sensor could come in handy.

With that in mind, a Japanese company has unveiled a prototype cell phone with a built-in bad-breath meter that will let you know if you need to reach for a mint. It also keeps track of your activity level, your pulse, and your paunch, thanks to a built-in pedometer, a pulse meter, and a body-fat analyzer, which sends a small electrical signal through your body to assess its composition.

The prototype Wellness Navigator--a slider phone with a touch screen, manufactured by Mitsubishi--was shown off last week at the Ceatec 2007 exhibition in Tokyo by Japan's NTT DoCoMo, one of the world's leading mobile providers.

Besides alerting users to their racing pulses and foul breath, the phone enables them to set exercise goals and share health data with friends and family. They can also track their caloric intake, using their typical daily diets to establish a baseline and adjusting for splurges by clicking pictures of pizza or spaghetti. Once customized, the phone offers users perky personalized messages encouraging them to keep exercising or get a good night's sleep.

NTT DoCoMo won't discuss its plans to market the phone or give any indication of how much it might sell for, but spokeswoman Makiko Furuta says that the target market is flabby middle-aged businessmen and diet-conscious young women.

The Wellness Navigator is the latest in a parade of Japanese cell-phone innovations, many of which have been slow to find a U.S. market. NTT DoCoMo customers can already pay for train rides, movie tickets, and groceries with a wave of their phones, and a phone that doubles as an alcohol breathalyzer has been popular with bus and taxi companies.

Pedometers and pulse meters have been available in small gadgets--wristwatches, for instance--for some time. But it's the new phone's "halitosis meter" that's piqued the most interest among tech enthusiasts and health experts alike.

Bad breath is a complex bouquet of gases, mostly sulfides, which a spouse--or a very good friend--can subjectively evaluate with a sniff. Objective assessment is harder. Gas chromatographs can provide detailed information about the chemical composition of an exhalation, but they're expensive and require trained operators. Sulfide monitors are used in many clinics, but they require regular recalibration, and they can't detect some of the stinky gases implicated in bad breath.

The Wellness Navigator incorporates a sensor that detects sulfides and ranks the user's breath on a scale of 1 to 10. However, "this notion that this little cell phone could do the work of this very elaborate equipment is just highly unlikely," says Pat Lenton, a research fellow at the Oral Health Clinical Research Center at the University of Minnesota.