The New Freshman 15 Is The “Fitbit 15”. A Cautionary Tale.

No Good Deed Goes Unpunished

They say that “No good deed goes unpunished.” In this case, it’s definitely the case. You get the schmancy wearable device complete with flashy lights, beeps, reminders, apps, it tells you your calories, steps, heart rate and billions of other things you didn’t even know that you needed to know!

So you invested in the tech. With all this data right on your wrist, you’d think that it will help you control weight. Unfortunately, the opposite turns out to be true. For individuals in weight management studies, those who have wearable devices often gain weight compared to those who do NOT have those devices.

What the, what? How can that be? First of all, you’d naturally think the device would assist in weight control. Second, why would it work against your efforts?

The Data Behind All That Data

It turns out that the information you receive on those devices may actually be responsible for the weight control failures. How?

Studies measured the accuracy of wearable device data  and found that “wearable devices had a rather high measurement accuracy with respect to heart rate, number of steps, distance, and sleep duration … whereas poor measurement accuracy was observed for energy consumption (calories)….”

Here’s a systematic review of many studies, that agreed that there was a “higher validity of

 steps, few studies on distance and physical activity, and lower validity for energy expenditure and sleep.”

Vanity Sizing, But For Calories

If you finish your daily walk and look down at your watch to find that you burned 2000 calories already this morning, you feel great! You LOVE this device! And you can totally justify a bacon triple cheeseburger! By systematically over-estimating the calories consumed, people over-compensate by over-eating over and over.

Hence the problem.

Ditch The Device?

Does this mean you should get rid your wearable? No, just be aware when you wear a wearable. The estimates you get from the device are just that … estimates.

What to do now? Do not use your estimated calorie burn to justify that Venti Caramel Macchiato. That said, if you want to use this information in some way, just be conservative and cut the number in half. Better yet, don’t modify your dietary intake based on perceived calorie offsets at all. Continue eating clean, and doing that in control. At that point, your schmancy device data becomes a wonderful little FYI, but not much more.