Faking your height to adjust your daily calorie adjustment

no44s4me

I've had a FitBit for over a year. First a Charge HR and now a Blaze. I've been very pleased with both, but through trial and error have deduced that the caloric burn FitBit gives me is too high. I've seen it alluded to a couple of times, but has anyone put a different height in FitBit to adjust their caloric burn?

tiffkittyw

Yes, mine is set to 5'3" and I'm really 5'4". This way I get a BMR in the 1,200's which matches the online calculators for my weight, height, and estimated body fat.

she_lived_wholly_forevermore

Mine seems to be pretty dead on but if it was burning too high I would just eat a little less than it gives me...

Christine_72

I reduced my stride length and height by 2 inches. Can't say I noticed a difference in calorie burn.

Yesterday I did 23,888 steps, 194 active minutes, 11 miles and got an extra 1,015 calories in mfp...

heybales

Yes, like @tiffkittyw - I adjusted height up so the BMR they used matched the better estimated Katch BMR.

And then of course manually corrected stride length since default based on height would be wrong.

But - I'm using a Zip, as such daily activity calories is fine with this change, and improved of course.
If I used step-based calorie burn for exercise it would still be correct, as that's based on your BMR.

But - if I had a HRM-based calorie burn for exercise - it would likely be fouled up now.
Because height and weight (BMI) is used in the calculation for HR-based calorie burn during exercise - and that BMI is now incorrect. Step-based calorie burn isn't used then.

The amount of difference would be unknown until you tested it.

Do a decent workout trying to stay at a set HR, then make your change, and then do the exact same workout - compare the calorie burn at the same average HR.

Mine would likely be major difference because my height went up 10 inches to correct BMR.

tiffkittyw

Hmmmm I wonder if since I went down a inch in my height if the HR based activities are more or less accurate now. I assumed more accurate since I've heard the Fitbit estimates high. I use workout mode on my charge HR for boot camp class (weights and cardio but very few steps, usually 1,000) and for elliptical and walking the Fitbit automatically tracks those work outs. I plan to track how Fitbit is calculating my TDEE the week of the 23rd since I don't have any events to attend and I can weigh 90% of the food I eat on a scale and get a good idea of my intake versus weight loss to see how accurate Fitbit is with calculating TDEE for me with its current settings.

heybales

Sadly as a woman 1 week won't be accurate either - because your BMR literally changes through the month. 150-250 cal difference between high and low.

1 inch isn't much of a difference for estimating calorie burn - more inaccuracies in food labeling than that would cause.

Plus the inaccuracy in using HR-based calorie burn for that type of workout would have it's own problems, since it's not the steady-state aerobic that HR formula is best estimate for. It's not on the other end of the extreme range like pure lifting at least, but still removed somewhat.

So even if you didn't have the inherent inaccuracy from changing BMR to effect the results - those other variables would make such an attempt difficult to know if you could pin it on the workout or other things.

But it still may be good for seeing if TDEE is decent for that week out of the month. Other weeks may vary other directions.

tiffkittyw

Thanks! Weight loss and weight maintenance sure is complex even with a Fitbit.

MzManiak

Fitbit seems to be pretty accurate for me, but I don't "log" exercise in MFP or Fitbit... I just let it adjust my calories on its own.