How FitBit Works

FitBit is evolving, from both a hardware and software perspective. In October 2011, the clip itself was upgraded and renamed the FitBit Ultra.

The Ultra has the same features as the original FitBit, with one major addition: an altimeter. With the altimeter, Ultra knows how much elevation you lose or gain throughout a day. That's valuable information because inclines are hard work. For example, if you climb the stairs in an 80-story building, you'll burn more calories than if you'd gone the same distance on a flat sidewalk outside.

In addition, the Ultra lets you check the time and includes a stopwatch so that you can manually time various activities. It displays so-called "chatter" messages, too, that are supposed to encourage you to keep moving (even though that super-sized milkshake is causing you some serious side cramps.

And of course, there are the aesthetics. The original FitBit featured teal accents; the Ultra comes with your choice of either blue or plum.

There's enough internal memory that the FitBit can store an entire week's worth of continuous data. Battery life is estimated at about three days, and you can check power levels at any time by plugging the unit into its base station.

FitBit doesn't track every kind of activity. It's not waterproof, so swimming is out. It can't tell that you just lifted weights for an hour, or that a rigorous yoga class just wiped you out. To bridge the gap, you can manually log activities through your Web account. Alternately, you can use the FitBit smartphone app (for iPhone or Android) to record workouts, as well as your food intake. The app doesn't let you upload data from your FitBit to your account, though. Only your computer-connected base station allows you to do that.

Once your data is synced to your online account, you have a plethora of options. You can check your daily, weekly and monthly stats, of course, as well as set goals. And you can create and monitor a food plan that helps you make better eating choices.

As you achieve specific goals, you'll unlock virtual badges that reward your positive behavior. These tokens recognize your achievements and push you to aim for loftier goals. You can also compare your stats with those of approved friends. Create an online group of friends or co-workers and together, you can share wisdom and inspiration that'll keep you on track.

By default, older versions of FitBit made your workout information public. Because of the potential for embarrassment, the company changed that setting. Now, your information is private until you configure it otherwise.

Curious about the FitBit's technology? Take a peek on the next page.

So you clip a little plastic widget to your clothes every day, hoping that it'll somehow magically transport you out of couch potato land and into healthful bliss. The process seems straightforward, but the technology is sophisticated.

The linchpin of FitBit is its three-dimensional accelerometer system. In plain language, that just means it tracks motion, as well as the intensity of that motion.

Then FitBit's software relies on special algorithms to convert raw accelerometer data into usable information. Those algorithms are the secret sauce that the company has worked diligently to tweak and improve, by experimenting and comparing FitBit's accuracy with other test machines.

For example, as the engineers test the "calories burned" feature, they compare FitBit's results with a portable telemetric gas analysis system. The latter analyzes gas composition as you exhale and very accurately determines your calorie usage.

With a lot of trial-and-error, FitBit has learned how to track and convert your energy expenditures (tracked by the accelerometer) into information about the number of calories you burn. Likewise, the company's testers have developed algorithms that work well for tracking the steps you take and how far you've moved.

The sleep tracking feature is more rudimentary. It merely logs how often you move throughout the night. So, if you're reading in bed and not moving the arm to which the FitBit is attached, it will think you're sleeping. Likewise, if you tend to flail about often during the night, the device may interpret your motions as meaning you're not sleeping at all.

In order for all of this to work properly in a population that differs greatly in physical characteristics, FitBit needs more information. Using your Web-based account, you enter personal information regarding age, weight, height and sex. You can also click to log your meals so that FitBit knows how many bacon triple cheeseburgers you need to work off.

Armed with your personal stats and a continuous stream of motion data, FitBit will keep you updated with information that tells you how much -- or how little -- activity your body is getting.

FitBit's healthy aims are a hit. FitBit's relatively affordable price and ease of use has won it a share of loyal users and some accolades. In 2009, FitBit was an Innovation honoree in the Health and Wellness category at the Consumer Electronics Show in Las Vegas.

But FitBit is only one product in a current trend of wearable fitness gadgets. It has plenty of competition. Jawbone's Up, for instance, is a wristband that tracks your movement and vibrates when you've been inactive for too long. It has a smartphone app and social networking features, too.

There are also more sophisticated (and more expensive) products for people who have both calories and cash to burn. The Basis Band is a watch-like device that comes loaded with sensors that track heart rate, movement and even galvanic skin response, which is a measurement of your stress levels.

The BodyMedia Fit is an armband equipped with four types of sensors that supposedly capture around 5,000 data points every minute. In addition to a motion sensor, it logs temperature, galvanic skin response and heat flux, which relates to the amount of heat that's dissipating from your body. Together, these sensors may provide a clearer picture of your overall activity and health.

And when it comes to monitoring sleep quality, it gets more complicated. Sleeping is highly variable and individualized behavior, and as such, there are many gadgets dedicated solely to tracking the quality of your rest. Those include the Lark sleep sensor, Zeo and others. If you really need sleep-related functions, you might be better off using something in this product category instead of a fitness gadget.

All of these products are tech-powered gadgets. In our Internet- and statistics-saturated age, devices like the FitBit really are a sign of the times. Will FitBit and its ilk help usher in a new era of health-consciousness? Or will they become obsolete and irrelevant in the face of our yearning to stuff ourselves with just one more sea-salt encrusted French fry?

Perhaps the social networking components of FitBit will propel it to greater success and help transform people into creatures who appreciate their physical fitness. Or maybe the gadgetry will just wind up on the car floor mats, wedged next to an empty fast food wrapper. Only time will tell, and when it does, you can bet that your fitness app will share it with the rest of your social network.

Up until a few years ago, my only exercise was short walks to and from the fridge.

Then, a persistent (read: incredibly annoying), running-obsessed friend finally convinced me to get outside and run, if only a few sluggish miles. She encouraged me to start slow, take my time and let my body adjust to new routines. The transformation was slow and not without struggle, but eventually, I got into the best shape of my life.

It was the consistent encouragement and goal tracking that helped me accomplish that feat. Gadgets like FitBit are kind of like having a friend who prods you along when you really don't feel up to worrying about your health. It keeps the issue front and center, every day, so that you learn to prioritize physical well-being. And as some people say, your health is all you have. If devices like these can give us better, longer lives, I'm all for them.

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