Fitbit giving insane (and erratic) amount of calories burned for walking

[uscpsycho]

Fitbit is giving me an INSANE amount of calories burned for walking. I am basing the knowledge and experience gained from a lifetime committed to fitness. But you don't have to trust my conclusions, here are two calculators that estimate how many calories you burn for a given amount of steps:

https://www.omnicalculator.com/sports/steps-to-calories

https://www.verywellfit.com/pedometer-steps-to-calories-converter-3882595

Today the crazy Fitbit app calculated that I burned 893 extra calories on 10,806 steps. The above two calculators estimate 441 calories and 479 calories for 11K steps. If you only walked 11K steps per day and ate 900 calories over your maintenance target every day, you would gain weight.

What's also crazy is how erratic the calorie estimation is. Yesterday I walked 10,370 steps but only burned 664 calories. The day before that I walked 10,434 and burned 767 calories.

None of this makes any sense whatsoever. Would love to hear how Fitbit comes up with such wildly inflated calorie estimations for walking.

None of this makes any sense whatsoever and so I can only ignore the Fitbit calorie calculation for steps because it is nonsensical and a great way to obesity.

[Heybales]

What was the total distance on each day?

Because calories per step would be silly as stride length changes depending on what you do, any calculators like that if any decency have huge footnotes on how on error prone their result is going to be and it should be for entertainment purposes only.

Calories is per distance, not steps - therefore how does the distance compare for the days?

And you are talking about days with similar step counts perhaps - but no or exact same workouts between them?

Forget steps that are hanging you up - while it's the easy to see metric, it's not directly related to calories.

The device uses your stride length setting and mass to estimate what an expected impact per step would be.

Variance to that means your stride length was different - so each step is given a distance right then.

Distance relates to calorie burn very accurately - studies have shown that walking between 2-4 mph level, and basing calculations on formula's, is much more accurate than the 15-25% accuracy a HRM may get if properly set up. And that's 15-25% either direction, not just inflated.

http://www.ncbi.nlm.nih.gov/pubmed/15570150

(4.2 kJ is 1 calorie. Notice the energy expenditure on treadmill and track is almost equal.)

That test Walking was 3.2 mph level for 1 mile for 19 min, calculation was 3.4 calories higher than tested 81 cal, or 4.2% higher.
Running at 6.3 mph level for 1 mile for 9.5 min, calculation was 4.8 calories lower than tested 115 cal, or 4.2% lower.

But if your distance is wrong....

And it can be.

Ever walked a known distance of 1/2 to 1 mile, and confirmed the Fitbit distance was correct?

[uscpsycho]

Your analysis about stride length and distance would matter if Fitbit had any idea how far I walked. But the app/band has no way of knowing how far I actually walked in a day and has no way of knowing if my stride length has changed from day to day. As far as Fitbit is concerned a step is a step and the calories per step should be static.

The only way what you are saying makes any sense is if the calorie burn calculated by Fitbit is not just based on steps but steps + additional variable(s). As far as I know Fitbit just takes your weight and calculates your calorie burn based on how many steps you walk. So if you walk 5,000 steps on consecutive days the calorie burn should be the same. If that is incorrect, what additional data is being considered?

Distance traveled and stride length cannot be variables used to calculate calories because Fitbit has no way of knowing these things.

[Heybales]

You are absolutely incorrect in your analysis.

Reread what I wrote for part of it. For rest of it...

Fitbit takes your BMR (gender, age, weight, height) and estimates daily that calorie burn. Biggest chunk of the day - static.

Daily activity (movement as shown by steps) is done by distance, which is dynamically calculated from the apparent distance of each step.

Exercise is done by HR-based calculations for calorie burn, and has many caveats to being a decent estimate, but sometimes even when poor it's the best. Some people's daily walking while more accurate with distance based, causes HR to go high enough that HR-based is used - very dynamic.

It absolutely does try to calculate distance - have you not seen the distance stats for your day?

Look at your 24 hr daily graph, while there you can also view per 15 min block calorie burn and see where it really went up for say a walk compared to just daily moving around.

You can also read up on what is now built in accelerometer calculations for movement. Fitbit doesn't even have to do the math anymore, it feeds into that chipset some values and results are spit out.