An increasing number of studies conclude that a diet's success or failure depends on simply decreasing the number of calories consumed. Be it a Mediterranean, Atkins, Weight Watchers, or South Beach diet, it's the caloric bottom line that matters.

"A repeatable trend is a more useful value than an accurate number," says Drinan. "The trend line helps you establish the pattern to your behavior." He says that the company is working with the largest device manufacturers, weight management, and pharmaceutical companies--"and none believe we need more sensitivity because of the long-term nature of the underlying problem."

PhiloMetron's prior ventures include the recently launched Corventis, which sells a sensor-based patch that detects the volume of fluid in a person with congestive heart failure and notifies her when it's time to take a diuretic. PhiloMetron plans to spin off another startup company to market a calorie monitor, with a product on the market in 18 months. Drinan envisions the product being sold through health-care professionals or personal trainers, or at gyms. But the system will cost a pretty penny: somewhere between $100 and $400, sold as a kit with multiple patches included.

"There's 1.6 billion people in the world who are overweight, and approximately 600 million of them are obese, so there's consumer applications all over the place here--for everything from weight management to part of disease-management programs, to consumer applications for fitness and wellness," says Jones of Qualcomm.

Eric Topol, director of the Scripps Translational Science Institute, in San Diego, and a practicing cardiologist, is interested in the device as a way to help keep his patients on track. He says that the technology is not only possible, it's reality: "Digestion and metabolic activity affects tissue conductance, and this can be detected via appropriate sensors worn on the skin."

Topol is interested in putting together a randomized clinical trial to see if the device can help people reverse type 2 diabetes, or help prevent progression to the disease in the first place. "I'm not suggesting that this is going to cure the obesity epidemic," he says. "[But] I think it has great potential--if it works and it's validated--to make an impact in the most common public-health problems today."