A Rant About Fitness Trackers

matthew's picture

I've recently been chiming in on the Garmin forums about my 910xt watch and Garmin VivoSmart. The frustration of users not knowing how to use their fitness trackers -- and blaming the devices for not being the magical weight loss talismans they thought they were! -- is palpable.

...I should have saved my $200 and just continued using the free myfitnesspal account and entering my estimated calories and got on with my life. I feel like such a sucker!...

First advice: if you felt as if you got more consistent results and inspiration sans a fitness tracker, return the fitness tracker. No need to have buyer's remorse.

General fitness tracker rant below :-)

So many buy a fitness tracker having "faith" that it would be accurate. They didn't do sufficient research before the purchase. Even gold-standard metabolic ward studies are typically accurate to no more than +/- 5%, which for a typical 2000-calore diet can be the difference between gaining or losing about a pound a month, simply due to the margin of error and individual differences between human beings.

Caloric intake on MyFitnessPal is precise, but slightly inaccurate. 100g of pineapple is ostensibly 43 calories. What about the core? The cap? Nearer the skin vs. further? Avocado blended with or without the pit? Which part of that Costco rotisserie chicken are you eating? The nutrition difference from seemingly small differences is enormous! It's the averages over time for a user's specific diet that a studious user will care about and use to guide their choices.

Fitness trackers are also fairly precise, but slightly inaccurate. Even the famous "BodyBugg" -- widely regarded as one of the most accurate fitness trackers to its indirect calorimetry method based on perspiration and body heat -- misses the mark by greater than 10% for many users, particularly as their biology changes over time (as they lose or gain weight, the Bugg is often slow to respond to the change and proffers inordinately-high calorie estimates).

One can use the combination of two precise but inaccurate instruments to still often create useful results. Trackers are a useful feedback mechanism, and the truth is that many people using Fitbits, Jawbone Up, and Nike Fuelband and other trackers gain weight rather than lose it: http://www.today.com/health/my-fitbit-making-me-fat-users-complain-weigh...

I would guess it's usually because they don't understand very well how to use the information provided by a fitness tracker, combined with under-estimating their consumption and over-estimating their exertion. If users watch their weight and body composition to gauge the accuracy of the device, they'll figure out these discrepancies within a month and adjust nutrition to achieve goals even using inaccurate measures like pretty much every fitness tracker currently in existence.

For examples of the supportive community surrounding the VivoSmart/VivoFit with MyFitnessPal (mostly VivoFit, because it is both older and vastly out-sells the VivoSmart), look to the MFP boards, rather than these Garmin boards:

It's not all bad, but for your personal happiness if this tracker isn't the right one for you, take it back! Garmin will sell millions more devices to numbers-geeks like me for whom a precise but slightly inaccurate measure is preferable to a straight-up estimate. However, both methods work just fine for weight loss, gain, or body recomposition!