Confused by MFP exercise calculation with FitBit

OnlyDragonQueen

its saying I burned 737 calories from two less than 30 minute walks around my neighborhood. Not strenuous, but more moving than I normally do. I dont get where it gets 737

janejellyroll

It's not saying that you burned 737 from the two walks, it's saying that you burned 737 more *all day* than what MFP projected given the activity level you provided. You will never see adjustments based on individual workouts on MFP, it's based on the estimate for the entire day.

Based on your weight and your activity level, MFP assumes that you need 2,435 calories to meet your goals. Fitbit estimates you have moved more than what MFP has assumed, so you're seeing that adjustment.

OnlyDragonQueen

Hmm, ok. I don't eat those points back, correct? It's telling me I was at like 800 calories left yesterday, when it subtracted those calories, but I didn't use them...it seemed odd.

cwolfman13

OnlyDragonQueen wrote: »

Hmm, ok. I don't eat those points back, correct? It's telling me I was at like 800 calories left yesterday, when it subtracted those calories, but I didn't use them...it seemed odd.

If your FitBit is giving you accurate figures, you would use those points. You're getting an adjustment because your FitBit is telling MFP that you're more active than whatever you selected in MFP.

Your FitBit is telling you that your estimated maintenance calories are 3,162 based on your stats and activity. If that is relatively accurate (mine is for me), eating 500 calories less than that would result in a roughly 1 Lb per week weight loss.

janejellyroll

OnlyDragonQueen wrote: »

Hmm, ok. I don't eat those points back, correct? It's telling me I was at like 800 calories left yesterday, when it subtracted those calories, but I didn't use them...it seemed odd.

The intention is for you to eat them back. MFP gave you a calorie goal assuming a certain level of activity. When you move more than they estimated you would, your calorie needs are higher.

Within a single day, it's no big deal to eat 700 calories less than your goal. But over time, it's the kind of thing that can cause issues so you don't want to make a habit of it.

Where people sometimes run into issues is when their Fitbit is overestimating their calorie burn (it happens for some people). If you're worried that this is potentially an over-estimate, you can start by just eating back a certain portion of them (say, 50-75%) and then observe your weight trend over a few weeks and adjust from there. I personally find my Fitbit to be accurate -- I eat back 100% of my adjustments.

Another thing that some people do is roll them over into subsequent days. If I have a very active day, I may not want to eat all the calories that day so I'll eat them over the next few.

OnlyDragonQueen

Alright, I suppose that's fair. It just makes me worried cause according to one site I should be consuming about 1400 calories to lose 2 lbs a week (resting/norm is about 2400 a day), that's with a light exercise life style, so it was just strange to see "oh actually, 1400 is too little, you need 2300" from taking 5k steps.

I guess testing the theory would work. It just seems like so much excess calories, ya know?

janejellyroll

OnlyDragonQueen wrote: »

Alright, I suppose that's fair. It just makes me worried cause according to one site I should be consuming about 1400 calories to lose 2 lbs a week (resting/norm is about 2400 a day), that's with a light exercise life style, so it was just strange to see "oh actually, 1400 is too little, you need 2300" from taking 5k steps.

I guess testing the theory would work. It just seems like so much excess calories, ya know?

I'm not sure what site you're referring to or how they reached that calculation, but 1,400 is a pretty low goal. Most women find they can eat more than that and lose weight, especially if they're also incorporating exercise into their lives. 1,400 would result in two pounds a week for someone who needed 2,400 to maintain. But according to your Fitbit, that's not you (on this particular day at least). If you're someone who needs 3,100 to maintain, then you'll want to adjust downward from there -- that would be about 2,100 calories a day to create a deficit to lose 2 pounds a week.

Now every day might not be that active, but that's the beauty of having the Fitbit synced. You don't have to do the math yourself, you'll just get the calculations of how much you need to add in order to reach your 1,000 calorie deficit (and, if you turn on negative adjustments, it will also *subtract* if you have a day that is less active than anticipated).

1,000 is a very aggressive deficit to shoot for in the first place so you want to make sure you're not accidentally making it larger by failing to account for your activity. In addition to making sure you keep your energy up, eating back your exercise calories makes it easier to meet your nutritional needs and helps you enjoy a wider variety of foods. And life is just more fun when you're not hungry all the time!

heybales

So MFP figured you'd burn 2425 calories for the day at whatever activity level you selected - and that was supposed to just be daily activity no exercise.

So beyond the facts mentioned above, that it was Fitbit that was ultimately the causes of that adjustment (by reporting you burned 2737 by almost 8 pm) - it means you had already burned 310 more calories by that point then MFP estimated you'd burn all day!

Now - Fitbit is getting that daily burn estimate from your BMR (got your stats correct on Fitbit?), and distance those steps took you.

Was the distance of the walks correct as Fitbit showed it if you know?

Did you create an activity for the walks when you did them?

Can you use MapMyWalk to confirm the distance, though even that's not super accurate?

That might give a clue if the distance is badly off.

The Fitbit may also have seen a high enough HR and those steps and turned on an activity automatically - and used HR based calorie burn - which for the bottom of the aerobic exercise range the walk was likely in - would be inflated calorie burn.
Distance based calorie burn would have been better.

Fitbit has 24 hr graph and you can find those increased steps, see if big increase to HR, and calorie burn.

Now - those walks are likely not the only thing you did that day - where else in your graph on the bigger calorie burns?
Really doing something active then?

nanastaci2020

Fitbit and MFP are both estimating your calorie needs for the day. MFP does this based on what you stated as your activity level. And Fitbit does it based on your actual movements. When Fitbit sends its data to MFP, MFP adjusts to correct its assumption vs actual.

Example:

Lets say your BMR is 75 per hour and for sedentary MFP expects you to burn a total (BMR and daily activity) of 90 per hour. MFP thus expects you to burn 2160 per day.

You wake up at 6am and sync. Fitbit credits you JUST for BMR for the time you were sleeping, because no movement. So Fitbit says you have burned 75 x 6 hours = 450. MFP expects 90 x 6 hours = 540, so you either see 0 adjustment or -90 if negatives are enabled.

Then between 6am-8am you're doing normal daily stuff. Not exercise, but you are moving as you get ready for your day. At 8am Fitbit says your total burn for the day so far is 650. For 8 hours into the day, MFP expected 720 so now you are at -70.

Fastforward. Lets say you did normal daily stuff for part of the day, but also went for a 60 minute walk where you were moving at a fairly brisk pace. Perhaps your day has you on your feet for a good bit (not a desk job for hours at a time) and its now 6pm. Fitbit says you have burned a total of 2250. MFP expected 90 x 18 or 1620, so your adjustment is +630.

Perhaps after 6pm, you don't sync again but also do not do much 'activity'. You move around a little, but pretty much your day is done. When you sync the next morning, Fitbit shows the prior day's total burn was 2750. MFP expected 24 x 90 or 2160, so your final adjustment for the day completed is 590. It went down slightly.

Its ok to assume that Fitbit is not 100% accurate - and leave some of those calories 'on the table'. You can judge by how you feel. If you feel energetic and satisfied on the calorie goal that MFP gives you initially, go with it. But if your new lifestyle is now more active than when you first started, consider at some point increasing your profile to the next activity level and using a little more calories per day. A more active person will ultimately need more sustenance.

nanastaci2020

Ps-in case there is any confusion: Fitbit is tracking your movement all the time, and calorie burn every minute/every hour of the day. Not just when you're walking for exercise.