Body Bugg utilizes a patented process for interpreting calorie burn called "sensor fusion" developed by BodyMedia, Inc. This process involves collecting a range of body-data using multiple physiological sensors instead of a single sensor, which is what other calorie estimation devices such as pedometers and heart rate monitors rely on. It's this multi-sensor approach that enables bodybugg™ to "see" the wearer's context (whether they are sitting, sleeping, jogging, walking, etc.) that makes bodybugg™ such a reliably accurate device for calorie expenditure estimation.

You can get them for $200 each but it seems awfully expensive because it's mostly something you can do yourself. You would only know how many calories you burn in a day. It comes with a 3 month subscription to the online program and after that you do have to buy more time online. Although it is reported to be 92+% accurate you have to be accurate about your food intake also.

It costs $15 a month after the first 3 months. You certainly don't need it to lose weight. In addition to telling you how many calories you've burned, it also has a pedometer which is amazingly accurate. I have bought several brands of pedometer in the past, and this is the first thing to be exact. And it doesn't matter what speed you're going or what your stride length is, it will be spot on.

The calorie readout is also very motivating. Many people find it so motivating to see what a big difference being just a little more active throughout the day can make. All those bits of advice in magazines that seem inconsequential do actually add up (walk to see your colleague instead of email, park a little further away, talk a little walk on your break, take the stairs instead of the elevator, etc.)

Once you upload your data, you can see charts that show your burn throughout the day, and how many calories you burn in a given minute (e.g. when you took the stairs you burned 5 calories/minute as opposed to 1 cal/min when you sat at your desk.) If you buy one, it is highly recommended getting the digital display which can be worn as a watch or clip onto your clothing.