My fitbit is making me fat — ridiculous claim or actually true?

Here’s the fitness industry’s dirty little secret: All those trackers, including the ones on your treadmill, stair climber and bike, are estimates. They are calculations based off of measurements culled from the average of larger populations of people. And while they can be accurate for some, this can make them wildly inaccurate for others.

I remember the first time I saw a Fitbit in action. The woman standing next to me in a kickboxing class shyly lifted up her shirt to show the tiny device clipped to her waistband, complete with a glowing flower. “It tracks everything!” she gushed.

Several months later she was no longer wearing the device. I never asked her why she quit Fitbit but she’s one of a growing number of people feeling disillusioned with health tracking gadgets like the Fitbit, the Nike Fuelband and Jawbone Up.

Korie Mulholland, who shared her story with The Today Show, is a perfect example. After losing weight on her own, she bought a Fitbit to help her get over a plateau. Yet even though she walked miles a day and ate the recommended number of calories her weight started to creep back up. “I used it for six months, until I gave up,” she says. “It was clearly telling me to eat too much for my specific metabolism and no matter what I did, it just wasn’t working right.”

More and more users are saying that even though they are following the directions to the letter they’re not losing weight, as shown by message boards filling up with frustrated customers.

Yet an inaccurate calculation is only one possible source of the problem. Weight loss and especially maintenance after losing weight is notoriously difficult. For some, working out too much could cause their metabolism to dip while others may be logging miles but not pushing themselves hard enough. Some people need less food than average to operate at good health while others, thanks to genetics, simply need more. Then there are issues like medical conditions, sleep, stress and other variables that affect your metabolism.

Plus, weight is a terrible measure of health. You may gain a few pounds as you put on muscle or lose a few pounds simply from eating a bunch of asparagus and peeing a lot. I also think they can encourage obsessive behavior when people get caught up in getting their numbers “just right.”

There are so many variables. Which is why it’s surprising to me this outcry didn’t happen earlier. The only way to accurately gauge your metabolic rate is to do a test where you breathe into a mask while a computer measures the rate of your oxygen consumption — not something most people want to do on a regular basis. And even then your metabolism can change over time. Health tracking gadgets are good for giving you an overall picture of your diet and fitness and can be positive motivational tools but in the end, they’re just estimates.

So if you’re one of those people who loves their tracker and sees good results with it, then stick with it. But there’s no point wasting money, time or mental energy if your Fitbit is giving you fits.

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