The BodyMedia Fit Core fitness armband ($179.99, retail, plus $6.95 per month for data access), used to calculate your exercise level and calorie burn, looks unlike other gadgets in its class. Two silver plates on the inside press against your skin to measure body temperature and galvanic skin response (perspiration, essentially). This, coupled with a three-axis accelerometer, helps BodyMedia calculate fairly accurate data. But there are drawbacks: You have to pay a monthly fee to see the data, and the armband itself is clunky, uncomfortable, and not particularly attractive.

BodyMedia's Body

BodyMedia Fit Core  faces the world strapped to your upper arm, and, unfortunately, it looks like a nugget-sized gray and eggshell-colored chunk of plastic with a small indicator light in the center. The light tells you when the battery is full or low. A rubber button next to the light lets you check whether the device is charged.

The reverse side, the area that touches your skin, has two silver plates with 10 small raised bumps and one larger bump. (See the slideshow for images.) On one side of the unit, not visible when worn, is a micro-USB port for connecting the BodyMedia to a computer to charge the battery and upload data. You have to connect it to sync the data, as the BodyMedia Fit Core doesn't have any wireless capabilities. There's an iOS and Android app that syncs with the Web-based Activity Manager so that you can see your data and log foods you eat while on the go. You can't sync the device itself to your smartphone, so you can only see the most recently uploaded information.

Another version of the same device, BodyMedia Fit Link ($199.99 direct), is nearly identical in functionality to BodyMedia Fit Core, except that it does have Bluetooth syncing capabilities, as well as slightly more attractive design.

The included armband, also a tinted gray eggshell color, is just a Velcro strap with a plastic ring where the BodyMedia snaps securely into place. 

Wearing BodyMedia

I used the gadget and the online system, called Activity Manager, for about a week, but three days in, and I decided to wear it overnight it anymore. The first time I slept with the armband on, I awoke to two huge red marks on my arm, which took all day to dissipate. I must have been sleeping on my arm, or positioned in some way to cause excess pressure. However it happened, I was not happy about it.

While wearing it during the day, I constantly readjusted the band, shifting it one way or another so that the metal plates were not in contact with the same patch of skin for too long. It's not the most comfortable thing to wear, and after day four, I was surprised that it felt more noticeable, not less.

At a nice restaurant one evening, I slipped off my cardigan only to have my boyfriend lean over the table and ask, "You're not going to keep that thing on during dinner, are you?" The BodyMedia is hard to ignore. It's in plain sight whenever your arms are exposed and is quite ugly. A light sweater may hide it, but anyone will still easily notice a huge and irregular bulge on one of your biceps.

Set Up and Fitness Information

As with most fitness measuring products, BodyMedia collects more accurate information if you give it a few metrics about yourself to start, such as gender, age, weight, height, and typical activity level (e.g., sedentary, moderately active, very active, etc.).

Out of the box, BodyMedia doesn't know anything about you. Setup involves plugging it into a computer and setting up the Activity Manager where you can enter these metrics, as well as log your food and beverage intake, record your daily weight, and see the statistics that BodyMedia collects. The first three months are free, but paying extra for the Activity Manager seems like an undue charge. Most fitness gadgets include access to the data in the purchase price. And the gadget itself is worthless without the data.

The website structures information well, and I had no trouble finding metrics like the number of steps taken in a day, how silently I slept, and where and how to input foods Id' eaten. The food area could be better, but its problems are typical of those I've seen with other calories-counting apps. The main issue is that it's very easy to log commercially packaged (that is, processed) foods, but tougher to find entries for foods that are minimally processed. For example, in looking for dried peas, I found dozens of branded options for canned peas, but nothing for fresh or dried peas. You have the option to create an entry for a new food or recipe (I logged a homemade spiced tea cake, for example), but I wish there a way to make recipes and new foods logged publicly available for others to share and use. A calorie-counting and fitness-tracking app called MyFitnessPal (free, 4 stars) does just that, and for those of us who eat a diverse diet, the shared information makes the app much better than most others.

As with all fitness gadgets and apps, you have to track both exercise and calories consumed to get good information back. If you don't log one or the other, you might see some very offputting numbers regarding how many calories you should be consuming in order to lose, gain, or maintain weight, depending on your goal (which you can enter in BodyMedia's system). The mobile apps only provide a snapshot of your fitness activity (calories burned, calories consumed, total steps taken, and a few other metrics), but they do let you enter foods that you've eaten throughout the day fairly easily.

Good Data, But It'll Cost You

A much simpler alternative to the BodyMedia Fit Core is Editors' Choice Fitbit Ultra ($99, 4 stars), a tiny, unobtrusive black clip that captures data nearly as well by relying on an intelligent pedometer and altimeter. Perhaps my favorite aspect of the Fitbit  is that it shows core figures, like steps taken or flights of stairs climbed, right on the device itself with no need for a computer or smartphone. You can always see the most important information in a second. Other devices, including the Jawbone UP , and Nike Fuel band, don't give you any data on the spot. A higher end fitness-MP3 player combo device called Motorola Moto Actv ($249, 3.5 stars) does make key information immediately visible on the device itself, too, but it's specifically suited to very athletic people and is meant to be worn during workouts and training only, not all day long or overnight.

Overall, the BodyMedia Fit Core collects good data, adding a few neat metrics skipped by other fitness devices, to report accurate estimates of calories input and expenditure. You have to pay an extra subscription to see that data, however, and with most other devices, free access to that information is included. BodyMedia is also unsightly and uncomfortable, whereas other modern fitness trackers, like the Fitbit Ultra, Nike Fuel Band, and Jawbone UP (the latter two have been sold out almost from the day they reached the market) are sleek and discreet. The Fitbit Ultra is surprisingly useful, and at just $99 should not be overlooked. It's also available widely, making it perhaps the only good option for most people.

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