As Americans have become increasingly overweight, manufacturers have responded by creating portable devices to help them shed those extra pounds by tracking their energy expenditure. You can use these devices to help manage your weight loss, track your calorie burn and even motivate yourself to change your behavior to become more physically fit.

Nike+ Fuelband

Nike+ Fuelband is an armband that measures your progress by a string of lights. The closer you are to the color green the closer you are to your goal. It is waterproof and has bluetooth pairing with any smartphone app. According to Consumer Reports, it is comfortable to wear 3. On the downside, people have reported skepticism regarding the amount of steps it tracks because of the differences in peoples' stride length, according to Consumer Reports.

BodyMedia

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BodyMedia is worn on your upper left arm and uses sensors to pull data off your body. It operates by measuring skin temperature, sweat response and the amount of heat generated from your body. You can log in your food intake, and it can track your sleeping pattern. In addition, you can have it send you positive messages. It does not include a heart rate monitor, and for some, it is very uncomfortable to wear around the bicep, according to Consumer Reports.

FitBit Ultra

FitBit Ultra is not a band but rather a clip that is worn on or near the wrist. This is a plus for most people, because it's comfortable to wear. The device measures the calories you burn by tracking the number of steps you take. It also tracks your sleep quality. It includes an altimeter, which is an altitude tracker. Consumer Reports notes that it is simple to use and comes with a USB plug-in. However, it is not waterproof, and the sleep tracker does not produce consistent results, according to Consumer Reports 3.

Tips and Caution

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Body-monitoring devices worn closer to the center of your body tend to be more accurate, because they measure overall body movement more clearly. If you wear a device on your limbs, it may not be as accurate because you generally move your limbs more than the rest of your body. The devices provide only estimates, not exact figures. Always check with your doctor prior to starting an exercise regimen or for more specific information on tracking weight-loss efforts.