***Story originally aired Jan. 21, 2014***

If you need a little motivation to lose weight and stay fit this year, an activity tracker may be the answer.

The wearable technology has become increasingly popular and can monitor everything from calorie count to the quality of your sleep.

Stores like Best Buy are having trouble keeping the fitness devices in stock this year.

The $130 Fitbit Force gets top marks from online reviewers and is Best Buy's number one seller right now.

The Fitbit works with your home computer or smartphone. It comes in several price ranges and styles, all which wirelessly sync with your smartphone. You can even buy a companion Wi-Fi smart scale that shares data tracks your weight and body fat.

On the downside, Fitbit Force users are reporting allergic reactions to the metal used to make the bracelet-like device. Fitness buffs with nickel sensitivities are advised to go for the Fitbit version that clasps onto your clothing or shoe.

The Misfit Shine is new to the market and sells for $120.

"It tracks your steps. It tracks your calories burned. It also has a watch and there’s an app you can download to your smartphone that wirelessly syncs all your progress so you can track it throughout the day," said Danielle Jang, Best Buy’s communication manager and Misfit Shine wearer.

On the downside, the Misfit only tracks steps and doesn't allow you to input specific exercises to boost your calorie burn.

Another hot seller is the $130 UP by Jawbone activity bracelet. 

"It will connect with your smartphone, IOS and android devices. It monitors how much you sleep, your movement, fitness activity for the day and you can actually key in what you've eaten," said Roopsy Sharma, Best Buy spokesperson.

The Jawbone bracelet doesn't work on your home computer, and it doesn't sync wirelessly either. You have to plug it into your smartphone to get a personalized, up to the minute look at how active or inactive you've been.

The Jawbone also monitors how well you're sleeping, how far you've walked and how many calories you've consumed that day.

So which one comes out on top?

Most reviewers and many consumers are giving the Fitbit the thumbs up, but there are a number of these devices on the market and more coming every month.

The good news is they seem to work at motivating people to exercise. Stanford's School of Medicine did a study that found using a simple pedometer helps you improve blood pressure, lose weight and increase physical activity by 2,000 steps, or about a mile a day.