Is Your Activity Tracker Holding You Back?

The thought of having burned a large amount of calories during your workout is often a very satisfying thing. You take pride in pushing yourself to the limit during your workout. You work until your heart rate is through the roof. Sweat is running off of your heated scalp and into your eyes. Peering through the sting of the sweat, you silence every thought about giving up; and powered through to completion, using the satisfaction of watching the number of calories being burned increase the more you grind. When you finally make it to the end you smile knowing it was all worth it when you see you racked up a total caloric burn in the high hundreds, or even broke into the thousands. You pat yourself on the back for your hard work and then your mind drifts to your post workout meal because you are ready to throw down. And this is where we begin to have problems…

Many fitness enthusiasts use the number on their activity tracker to estimate how many extra calories that they can consume throughout the course of the day. This is a problem on a couple of levels. One being that, more often than not, the number on your activity tracker is grossly over-estimated.  Gauging your caloric needs from this figure could be leading you to over estimate your total daily expenditure (TDEE). Doing this on a regular could be a contributing factor to weight-loss plateaus, or even unwanted weight gain.

Here is an interesting study [1] that supports the thought that the number on your activity tracker could be affecting your eating habits, and not in the way that you would like. Here, a group of 70 male and female participants were made to exercise until they burned an estimated 120kcals but some were informed that they only burned 50kcals while the others were told that they burned 265kcals. They then observed the eating patterns of the participants post exercise when given meal options of tortilla chips, orange juice and chocolate chip cookies. Here is what they found:

” Greater EI, primarily driven by chocolate chip cookie consumption (p = 0.015), was observed in participants receiving 265 kcal EE information. Hunger ratings were significantly lower in the 265 kcal EE information group than in the 50 kcal group following the test meal (p = 0.035), but not immediately after the exercise.”

So what they are saying is that the participants who were informed that they burned 265kcals were the ones prone to indulge in the chocolate chip cookies, while the 50kcal group showed greater restraint. The 265kcal group experienced reduced hunger after the meal but not immediately after the exercise. So the findings suggest that these activity trackers that are over-estimating your caloric expenditure could be counter productive to your attitude towards food post-workout. In the study the term ‘license to eat’ is used and that’s why the over-estimated number can be a problem. You do have a license to eat as you need to fuel your body but your device may be causing you to overindulge.

My advice? Use your activity tracker as motivation to push yourself in your workouts. You can use the numbers listed to help you keep your workout intensity consistent or as a way to push past previous intensities. However, I’d advise against using an activity tracker that claims that you burned 600kcals in a 60-90 minute resistance training workout to gauge your caloric needs as such numbers are wholly unrealistic, and inconsistent [2], especially when such figures are being displayed for women, without any specific calibration.

Instead, base your TDEE estimations off of the average length and intensity of your workouts over the week [3-5]. If your workouts tend to be of a moderate intensity in general then estimate with that in mind. Any extra caloric expenditure from those days where you put in a little extra work should just be considered a bonus, especially when weight loss in the goal. Since we tend to overestimate our caloric expenditure this is often the safest course of action to avoid unnecessary setbacks.

1. McCaig DC, Hawkins LA, Rogers PJ. Licence to eat: Information on energy expended during exercise affects subsequent energy intake. Appetite. 2016 Dec 1;107:323-329.
2. Zeni AI, Hoffman MD, Clifford PS. Energy expenditure with indoor exercise machines. JAMA. 1996 May 8;275(18):1424-1427.
3. Hall C, Figueroa A, Fernhall B, Kanaley JA. Energy expenditure of walking and running: comparison with prediction equations. Med Sci Sports Exerc. 2004 Dec;36(12):2128-34.
4. Greiwe JS, Kohrt WM. Energy expenditure during walking and jogging. J Sports Med Phys Fitness. 2000 Dec;40(4):297-302.
5. Loftin M, Waddell DE, Robinson JH, Owens SG. Comparison of energy expenditure to walk or run a mile in adult normal weight and overweight men and women. J Strength Cond Res. 2010 Oct;24(10):2794-8.

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