Trusting fitbit numbers

aliciab307

Stats
24, F
196lbs~
37.6%bf~
Lift 4-5x/wk
Zumba 2x/wk
Walk 10-22k/day

Ok so I have the fbChargeHR. And for the past 2 wks my avg burn is 4.1k-wk 1, 4k-wk 2.

What is the margin of error for fitbit, if anyone knows? I'm wondering how much I should trust FB numbers. Lifting sessions are about 30-60 mins, zumba is about 45-60 mins

madierdorf

I don't know but with my flex I changed to dominant arm and my numbers went down alot for steps. Not sure why. I struggle to reach 10000 usually between 6-8900 . I run ,do karate , taking the stairs instead of elevator ...it is curious I must say. Good luck and keep on going:-)

perseverance14

It is always too low for mine, but I have a One, by about 200-300 most days.

aliciab307

Thanks guys. Just wondering how much I should eat according to what fitbit says I burn. I wear my fitbit on my non-dominant arm and the settings match the same. Think I'll try dominant arm today to see what the numbers say.

I will say that right now I'm eating 2700 calories and not gaining and sometimes I am hungry at the end of the day. I guess that alone could mean I am burning more than I think? I'm aiming for 1lb/wk so I was going to up cals from 2700 to 3400.

ILiftHeavyAcrylics

Mine estimates low for me, which is good because it gives me a buffer to be over my calories occasionally. Overall I've eaten back all of my fitbit calories and maintained (which is my goal) for 10 months or so.

aliciab307

Tha

ILiftHeavyAcrylics wrote: »

Mine estimates low for me, which is good because it gives me a buffer to be over my calories occasionally. Overall I've eaten back all of my fitbit calories and maintained (which is my goal) for 10 months or so.

Thanks for the feedback. Which fitbit do you have? And if a wristband which arm do you wear it on?

shadow2soul

The best way to figure out it's accuracy for you is to follow it for a couple weeks (4-6) and see if your weight loss matches what is expected for your average intake/burn (fitbit displays 30 day averages on your profile page).

For example:
30 Day average Burn from Fitbit Surge - 2483
30 Day average intake - 2006
30 Day average deficit - 477
477*30= 14310
14310/3500 = 4.088...
Weight lost = 4.7

So for the past 30 days, mine hasn't been 100% accurate, but so far it isn't overestimating either.

aliciab307

shadow2soul wrote: »

The best way to figure out it's accuracy for you is to follow it for a couple weeks (4-6) and see if your weight loss matches what is expected for your average intake/burn (fitbit displays 30 day averages on your profile page).

For example:
30 Day average Burn from Fitbit Surge - 2483
30 Day average intake - 2006
30 Day average deficit - 477
477*30= 14310
14310/3500 = 4.088...
Weight lost = 4.7

So for the past 30 days, mine hasn't been 100% accurate, but so far it isn't overestimating either.

Thanks. I'm going to start that today. Just afraid of eating 3400 cals! Do you wear yours on dominant or nondominant? I've been wearing mine on non dominant but trying out dominant today. Wondering how different the numbers will be for each arm.

thorsonej

shadow2soul wrote: »

The best way to figure out it's accuracy for you is to follow it for a couple weeks (4-6) and see if your weight loss matches what is expected for your average intake/burn (fitbit displays 30 day averages on your profile page).

For example:
30 Day average Burn from Fitbit Surge - 2483
30 Day average intake - 2006
30 Day average deficit - 477
477*30= 14310
14310/3500 = 4.088...
Weight lost = 4.7

So for the past 30 days, mine hasn't been 100% accurate, but so far it isn't overestimating either.

Interesting. I just did mine, and came up with similar results.

30 day average burn: 3082
30 day average intake: 2659 (all food is weighed, so this should be relatively accurate)
30 day average deficit: 423
423*30=12690
12690/3500=3.63lbs
Actual weight loss: 3.7lbs

I'd say that's pretty darn accurate.

For reference, I have a One.

lzepeda89

ILiftHeavyAcrylics wrote: »

Mine estimates low for me, which is good because it gives me a buffer to be over my calories occasionally. Overall I've eaten back all of my fitbit calories and maintained (which is my goal) for 10 months or so.

Same here. I know for a fact my calorie counts are under what I normally do, which is a good thing like they said it gives me a buffer.

retirehappy

aliciab307 wrote: »

Thanks guys. Just wondering how much I should eat according to what fitbit says I burn. I wear my fitbit on my non-dominant arm and the settings match the same. Think I'll try dominant arm today to see what the numbers say.

I will say that right now I'm eating 2700 calories and not gaining and sometimes I am hungry at the end of the day. I guess that alone could mean I am burning more than I think? I'm aiming for 1lb/wk so I was going to up cals from 2700 to 3400.

That is a huge jump in cals. I suggest you try adding 100 cals per day and see what the results are. Are you trying to maintain, lose, or gain? See if you see a difference.

You are very active are you hungry or just bored? Sounds like you ROCK your days.

aliciab307

Lol

retirehappy wrote: »

aliciab307 wrote: »

Thanks guys. Just wondering how much I should eat according to what fitbit says I burn. I wear my fitbit on my non-dominant arm and the settings match the same. Think I'll try dominant arm today to see what the numbers say.

I will say that right now I'm eating 2700 calories and not gaining and sometimes I am hungry at the end of the day. I guess that alone could mean I am burning more than I think? I'm aiming for 1lb/wk so I was going to up cals from 2700 to 3400.

That is a huge jump in cals. I suggest you try adding 100 cals per day and see what the results are. Are you trying to maintain, lose, or gain? See if you see a difference.

You are very active are you hungry or just bored? Sounds like you ROCK your days.

Wanting to lose 20-30 lbs. zumba is for fun, i lift for strength and physique, and walk so I'm not just sitting all day at work. My goal has been 2700 but for the past few days I've been eating 3000-3100 due to hunger.

For reference zumba is about 50-60min/session. Lifting is 20-45 mins depending on body part worked.

shadow2soul

aliciab307 wrote: »

shadow2soul wrote: »

The best way to figure out it's accuracy for you is to follow it for a couple weeks (4-6) and see if your weight loss matches what is expected for your average intake/burn (fitbit displays 30 day averages on your profile page).

For example:
30 Day average Burn from Fitbit Surge - 2483
30 Day average intake - 2006
30 Day average deficit - 477
477*30= 14310
14310/3500 = 4.088...
Weight lost = 4.7

So for the past 30 days, mine hasn't been 100% accurate, but so far it isn't overestimating either.

Thanks. I'm going to start that today. Just afraid of eating 3400 cals! Do you wear yours on dominant or nondominant? I've been wearing mine on non dominant but trying out dominant today. Wondering how different the numbers will be for each arm.

I have been alternating here lately. After 2 weeks of wearing it on my non-dominate hand I ended up with a rash under the rubber part of the band, but I think I might have been wearing it too tight. Now I only tighten it during exercise and I wash the band after I workout. I'm alternating weekly now. So far it doesn't seem to make a difference on calorie burns/step counts or anything like that. If it is effecting them, it's not a big enough difference for me to notice.

aliciab307

shadow2soul wrote: »

I have been alternating here lately. After 2 weeks of wearing it on my non-dominate hand I ended up with a rash under the rubber part of the band, but I think I might have been wearing it too tight. Now I only tighten it during exercise and I wash the band after I workout. I'm alternating weekly now. So far it doesn't seem to make a difference on calorie burns/step counts or anything like that. If it is effecting them, it's not a big enough difference for me to notice.

Thats great to know. So far step count has been fine. Thanks

kuranda10

I just "tested" my Charge HR using the formula above and it's not bad.

If anything it's slightly underestimating, which is OK for me.

editorgrrl

The only way to gauge the accuracy of your Fitbit is to trust it for several weeks then reevaluate your results.

I have a Fitbit Flex & log exercise in Fitbit—never MFP. I eat back all my adjustments, lost the weight, and have maintained for 8 months. So my Fitbit burn is my TDEE (total daily energy expenditure).

It will take trial & error to find what works for you.

heybales

Lifting is going to be an inflated calorie burn if calculated by HRM readings - totally wrong use of the formula.

HRM formula is ONLY valid for steady-state aerobic, same HR for 2-4 min.

If lifting correctly, it should be totally opposite of that state.

Step based or HR based calorie burn devices should have lifting manually logged.

Weights on Fitbit database, Strength Training on MFP database.

With corrected numbers (you can correct past 2 weeks if you have decent estimate of time start and duration), how does the TDEE look now?

Walking daily should be accurate, but you'd need to get a handle on if the steps seen accurate.
If getting a lot of extra steps, then that's inflated too.

oludi

I love the individual workout stats

aliciab307

As far as lifting, if inflated then my burn must be very low. range from 100-400 cals depending on length of workout. Some lifting sessions are more endurance based and HR increases like I'm doing cardio.

So if I correct the numbers, how would I correct? Just add exercise as lifting and add time and let fitbit calculate burn?

I checked and steps are accurate. Placed on dominant wrist to prevent extra steps.

heybales

aliciab307 wrote: »

As far as lifting, if inflated then my burn must be very low. range from 100-400 cals depending on length of workout. Some lifting sessions are more endurance based and HR increases like I'm doing cardio.

So if I correct the numbers, how would I correct? Just add exercise as lifting and add time and let fitbit calculate burn?

I checked and steps are accurate. Placed on dominant wrist to prevent extra steps.

Correct, compared to cardio it is low.
Depending on how strong a workout, and amount of repair body does in next 24-36 hrs, you'll get increased calorie burn then, but that is even harder to determine. Free fat loss deficit really.

Weights is sets and rep ranges 4-15, rests of 2-4 min.
Circuit training is rep ranges over 15, rests up to 1 min, multiple circuits.
Calisthenics is rep ranges over 20, minimal rests, usually body weight.

The closer your workout is to the bottom there, the closer to a better estimate the HR formula can give, since as you've observed, cardio-like HR increase and long duration.

3JinItaly

Hi everyone! So from what I'm reading, I am to only enter my activity into the fitbit and food into mfp. Correct? The amount of calories that my fitbit is telling me to eat is a LOT extra and it seems like too much!

I lost 22lbs. pretty quickly by using mfp and starting to exercise regularly, but now I have been plateaued for almost 9 weeks! I have tried every combination that I know to try and nothing is working!

I am a short 5'4" and weight 151lbs. I live in Italy, so I walk everywhere and on a slow day, clock in at minimum 12,000 steps. Some days upwards of 15,000. I also do the Jamie Eason strength trainer program of weightlifting 4 days a week and a kickboxing class 6 days a week. So, yes, I'm working out/moving a lot. There is such conflicting information though about should you eat back calories, should you set your activity level lower, etc. and I literally don't know what the right combination is. I've been eating around 1600 calories more or less and now I'm starting to think that perhaps its not enough. Some websites say that starvation mode is just a myth while others say its a real thing, and I don't know what to believe.

So, perhaps for the next week, I will trust my fitbit and eat back the calories that it tells me to, just to see what happens.

Any thoughts about its accuracy??

kuranda10

I use to walk at least 12,000 steps a day and I started losing weight again when I upped my calories to the 1800 range.
My BMR is 1400, so it stands to reason I need a lot more than the extra 200 calories to do everything else (like get dressed and eat) and then add 12,000 steps on top of that.

Today FitBit tells me my TDEE is already at 2300. If I only ate 1600 calories that would be a HUGE deficit.

One thing I do like about the FB is I am constantly changing my TDEE so I can eat accordingly. It also keeps my body from getting "used to" operating with a certain number of calories.

3JinItaly

Thanks! I had a feeling that I was probably depriving myself, but it seems so counterintuitive to eat that many more calories when your body is used to eating less. It seems like so much! Today already, fitbit has given me an extra 733 calories back. That's crazy!!

NancyN795

3JinItaly wrote: »

Thanks! I had a feeling that I was probably depriving myself, but it seems so counterintuitive to eat that many more calories when your body is used to eating less. It seems like so much! Today already, fitbit has given me an extra 733 calories back. That's crazy!!

Actually, that sounds reasonable. Yesterday I took >17000 steps including a short Zumba class, a 3 mile power walk and a little weight lifting. FitBit gave me an extra 1079 calories.

In the past, I haven't been good about weighing and measuring every bite I eat, but I have been trying to be very diligent about that for the last few weeks (I had stopped losing and even gained back a little). In the last two weeks, my weight loss has been very close to what would be predicted by the calorie deficit shown in my FitBit weekly report.

So, go ahead and eat those calories. Just measure your food carefully.

heybales

3JinItaly wrote: »

Thanks! I had a feeling that I was probably depriving myself, but it seems so counterintuitive to eat that many more calories when your body is used to eating less. It seems like so much! Today already, fitbit has given me an extra 733 calories back. That's crazy!!

until you have logged what you used to eat that caused a very slow gain, before even exercising, you like majority of others probably have no idea about calorie levels.

All you've seen are the low ball bare minimum diets of 1200. For the average sedentary woman to just get all nutrients in.
Not for body improvements, nor for performance, not for aesthetics, only for safety of a barely healthy body.

So good job being willing to eat at healthier level. And depending on amount left to lose, people can still pick unreasonable loss goals that will still create a fight with their body and stress.

You'll know when that 9 weeks turns in to multi-months.

At which point even a slow loss choice would have been faster than no loss for months on end, like many end up with.

kspenglermoore

I do not have the new fitbit with HR, but I seen few test reviews (the best one was one where the person was linked to an EKG machine at the same time) for wristbased HR monitors and they were almost all off, mostly underestimating. I ended up buying a polar HR monitor with a cheststrap. It also caculates my calories burnt based on my age, sex, weight and height during exercise. I record the calories, the distance and kind of exercise manually in my fitbit with the phone app and then let it adjust MFP accordingly. That seems to be the most accurate way of doing it. I have also found that the non-dominant hand gives higher numbers. I do like my fitbit to help keep me moving during the day...... I have lost 105lbs in 10 month and have now been maintaing for 3 month..... I NEVER eat all the calories I have according to MFP. I usually stay around 500 calories under and that seems to be working well. As to being hungry at the end of the day my suggestion is look at what you eat. I keep my fat to around 20% and my protein at at least 30%. I eat more fiber then suggested, but usually end up with a little less then 50 % carbs.

Robbnva

There's definitely a margin of error. I get steps counted after washing my hands...