Photo: bodybugg.com

Have you ever watched "The Biggest Loser" and wondered about those arm bands the contestants wear? The device is called the bodybugg, and there's some pretty nifty science contained within. The bodybugg is a little black box that straps to your right upper arm, containing sensors that sit on your skin. It tracks weight loss by measuring how your body moves, sweats and rests. At the end of the day, you download the collected information to a computer, and a sophisticated software program calculates how many calories you've burned.

The software connects with an online food journal so you also keep track of how many calories you've eaten. I've owned one for three years and can attest to the its accuracy. I call it my conscience; it's like having a nutritionist and a trainer sitting on your shoulder 24/7 and flicking you in the back of the head to make sure you keep on track.

I spoke with Kim Slover, the service manager for Apex bodybugg, who gave me the inside scoop about the science behind the device. "There is not another tool on the planet that can track your total calorie expenditure like the bodybugg does. It has greater than 90 percent accuracy," said Slover. She explains the device tracks six different pieces of data: Your heat flux, your core body temperature, your sweat rate, what axis of motion you're tracking on, your physical activity and a your steps. It also syncs up to software that tracks your body's progress, allows you to set weight loss goals and includes a detailed nutritional log.

When I first received my bodybugg, I had to wear it overnight to establish baseline readings. I found I woke up when I rolled over onto my arm, but it was only for two nights. It also took some getting used to having it on constantly, as adjusting to the strap takes a while. Plus, you can't really wear it with tight fitting clothes, and you can also develop a rash if you don't keep it clean. I found my skin would dry out under the device, and I had to apply a little extra moisturizer, too. But, for me, these inconveniences were far outweighed by what I was learning about my fitness and nutrition routines. At first I found myself downloading data to the computer after every workout to see exactly how many calories I had burned per minute during certain exercises. It's kind of fun to see how many calories you burn watching TV (not much) or while trying on clothes at the mall (surprisingly high!). I also would often download my information in the afternoon to determine how many calories I had left for dinner. This worked really well and would let me know if I should load up on veggies or go ahead and have extra rice. With the bodybugg you can't "fudge" how many calories you burned during your workout; if the bodybugg says you burned 351 calories, then that's almost exactly what you burned. Yes, you can still "cheat" with what you enter into your online food journal, but if your goal is losing weight, what do you gain by doing that (except extra pounds)?

I like this device particularly for diabetics, as the journal breaks down food into its macro-components, allowing you to track how many grams of fat you eat per day and the nutritional content of the food you're consuming. The bodybugg also comes with a phone coach to walk you through the software set-up and how to download data, as well as how to set weight-loss goals and give some suggestions for a fitness routine.

Finally, I did get a little bit of "Biggest Loser" gossip from Slover. Since the contestants began using bodybuggs in season 4, "the biggest losers for each season were the biggest bodybugg users," she said. "These folks were logging in on a daily basis, and they had the best results."

For more information, go to bodybugg.com. The retail price is between $199 and $249.

Are you aware of how much calorie burn you get from certain exercises? Take this quiz to find out.