How accurate is your Blaze calorie count?

[Veteq83]

I've come to the conclusion that my FitBit Blaze is overestimating calories burned by 20-25%.

I'm a fairly big guy: 34, 6'2" and currently at 243.7 lbs and 28.6% bodyfat, according to my Aria, and who knows how accurate that is. Every day I go to the gym and do about 45 minutes of relatively intense weight training (I used to powerlift in my younger days) and 30 minutes of cardio, usually on an elliptical with a target heart rate of 150 - 160 bpm. I also take my dog for two 30 minute, brisk-paced walks per day. Most of the rest of my day isn't too active; working, running errands, facebooking, but I often walk if I need to go somewhere fairly close to home.

Regularly my fitbit records 4,600 to 5,000 calories per day. Sometimes it's over 5,200 and rarely is it under 4,500.

I am meticulous about recording calories: I weigh, measure and record everything, from the milk for my coffee to each and every bit of steak or chicken. Rarely to I eat prepackaged food (too much sodium) and never do I eat out anymore. I'm averaging a caloric intake of about 2,300 per day; about an average 2,500 cal/day deficit according to FitBit.

You might think, "wow, that's nuts! The weight should be dripping off you". But it's actually falling at a respectable 2.5 lbs/week average. Now I'm not complaining about that, nor do I have a problem with it.

The problem is that according to my fitbit numbers I should be losing somewhere near 5 lbs/week! Which would be unhealthy. However, if I wasn't paying attention, followed the dietary guidance of FitBit and trusted the numbers given to me, I'd be gaining weight at their suggested 1,000 cal/week deficit and eating almost 4,000 calories a day.

Obviously an average nearly 5,000 calorie burn rate per day for a normal person without a highly active job is ridiculous. So the only conclusion is my FitBit is way, way off.

Anybody else notice this discrepancy?

Almost makes me feel this thing is useless and I'm about to ditch it for a smart watch.

[AlejandraFitbit]

It's great to see you around @Veteq83.

If you are seeing that your calories are not being accurate, I recommend verifying that your personal and food plan information are correct. Also, for more information about calories, I recommend taking a look at our How does Fitbit estimate how many calories I've burned? article.

Catch you later. 

[Veteq83]

Yes, all my inputted information is correct; the technology is faulty. 

[Joemf88]

So that's it to this thread? I was seeing that my blaze was saying that my calorie burn is around 3000. Is this right? I need to know how accurate this device is. I am in IT and do no exercise. I eat like crap too. So I am not active. 3000?!?!? Seems sketchy...

[ScaredChicken]

For me, if I subtract my Basal metabolic rate based my height age and gender from the fitibit total for the day and then multiply the remainder by 0.75 and add back in my BMR, then it’s spot on.

[jwright1014]

I've had a very similar experience to ScaredChicken.  If I adjust the excess calorie burn over the BMR by about 75%, then my actual weight loss calculations over a long period of time are very much in line with the expected weight loss based on the adjusted calorie deficit.

[Ari_ana]

On average, the human body needs 1800-2000 cal approx for women and 2200-2500 cal for men just to live at a maintained level for one day. When I do sedentary work for a day I tend to only burn around that 1800-2000 cal mark. However, when I gym (weightlifting) and walk 10,000-20,000 steps in a day I burn around 3000-3500 calories according to my Fitbit blaze. Which would be approximately accurate for me. 

So if you’re hardly moving then it might be off by a few hundred calories. Best bet is to do a manual calculation for the amount of steps you do in a day to see if it’s similar. 

My fitbit blaze tends to think I’ve done 20-50steps before I wake up so... accuracy.. ??? 

[Ari_ana]

Sorry that reply was for joem88

[SunsetRunner]

How do I do that? 

[LaJefa]

The BMI-Total caloric intake for the day x0.75+ BMR gives you the appropriate deficit?

[Qtrix]

Can you explain abit more about how you do that? So are you saying out the total calories burned from the day you minus your BMR and than x0.75 than you get your actual calories burned for the day?

[ScaredChicken]

Right, so I take the Fitbit daily caloric, subtract my BMR and that value that results I multiply by 0.75 and then add back in my BMR to get my true caloric burn for the day (or TDEE, Total Daily Energy Expenditure).

So:

TDEE = (Fitbit caloric value - BMR)*0.75 + BMR

then intake that amount of calories (your TDEE) to maintain your current weight or eat a surplus of 250-500 cal per day to gain 0.5-1.0 lbs per week or eat a deficit of 250-500 cal per day to lose 0.5-1.0 lbs per week, etc. 

Hope this helps!