If you're in the market for a daily activity tracker, chances are you're looking at the Fitbit or BodyMedia. Either one can help in your quest to get fit or lose weight. While they are similar in function and price, there are some differences to be aware of when trying to decide which one to buy.
Fitbit tracks activities such as steps taken, stairs climbed and distance traveled using a built-in accelerometer and altimeter. It also uses information you enter into your profile -- such as your gender and weight -- to calculate your caloric burn for the day. BodyMedia also tracks the steps you take. Unlike the Fitbit, it uses sensors to monitor your movement, skin temperature, heat flux and galvanic skin response to calculate your activity level and caloric burn. This gives you insight to how hard you are working during your activity. Activity is displayed in the online tracker as "Moderate," or "Vigorous." Moderate activity falls within the three to six METS range -- such as walking, housework and gardening. Vigorous activity is anything more than six METS -- such as running, fast cycling and aerobics.
A study conducted at the University of Wisconsin showed that both devices accurately count steps for most activities. The Fitbit was found to underestimate steps during treadmill running and neither was accurate for agility training. As for caloric burn, the BodyMedia was found to underestimate caloric burn for treadmill running, elliptical training and agility training. Fitbit underestimated caloric burned during agility training, according to the study.
Both units monitor sleep, recognizing its importance in weight loss. Fitbit tracks the number of hours you sleep as well as how many times you wake during the night. The unit also has a silent vibrating alarm that will wake you while allowing your partner to continue sleeping. BodyMedia tracks only the number of hours you sleep. It does continue to monitor all other measurements as you sleep, calculating calories burned. The accuracy of sleep monitoring in either device is unknown, as independent studies have not been done on this feature.
Both Fitbit and BodyMedia have online interfaces that allow you to view your activity and track progress, as well as smartphone apps. Both interfaces also integrate with partner sites such as Runkeeper and MyFitnessPal. Fitbit's online tracker is free. You can upgrade to a premium membership that adds in a digital trainer, benchmarking, additional reports and other features for an annual fee. Data is continuously synchronized wirelessly and available via your phone. There also is a social component that allows you to connect with friends and compare your progress to theirs. BodyMedia's online tracker carries a monthly fee. Data is synchronized by plugging the unit into your computer using a USB cable. Or, you can buy the Bluetooth version -- at a higher price -- that will sync wirelessly with your phone at the touch of a button.
Wearing the Unit
Fitbit has a few options when it comes to buying a unit. Units are available that clip onto your clothing or that you can wear like a watch. Either option can be easily hidden and is unobtrusive. By contrast, you wear the BodyMedia unit on your arm with an armband. It's clearly visible when you wear short sleeves and carries some bulk, showing under long sleeves as well.