How does the Fitbit Calorie adjustment work?

butterflyfaerie

Sorry if this has been asked before! But just trying to find out if I still need to add workouts I've done through Fitbit to MFP, or if these calories are recorded in the Fitbit calorie adjustment.

I ask because I recorded some swimming the other day, and my previously positive adjustment changed to a negative. Additionally, I then did some dancing that I recorded on Fitbit, and when adding it to MFP, my adjustment was even lower than it previously was.

But on the flip side of the coin, I'm worried if I DON'T record the activities, then MFP will be showing the wrong amount of exercise calories. Other than this uncertainty, I really like the integration between the two, just this little hiccup has me worried!

LivingtheLeanDream

There is a dedicated Fitbit group here but I'll tell ya anyway
Log your food only on MFP and your exercise on Fitbit, which will sync and adjust your total calories burned on MFP.

Have you changed the MFP settings to 'enable negative adjustments' and what activity level have you set MFP to?

What happened for you the other day is normal, Fitbit would have given you a burn for your activity but since you logged it yourself it then took it off so you weren't doubly posting.

StaciMarie1974

A long detailed explanation of how it works:

When you use MFP alone: you enter your height/weight/age/gender and choose an activity level. MFP uses this data to estimate how much you'll burn in a day. Lets say its 2400/day. Example only... You then say you want to lose 2 pounds a week so MFP says eat 1400. Due to 2400-1000 = 1400. MFP has no way of knowing if your stated activity level is accurate.

When you use Fitbit, it uses your stats and actual movement to estimate your calorie burn. When you sync the two, MFP gets that data and compares it to MFP's own prediction. If your actual is greater, then you earn additional calories. And the details change thru the day as you move.

Using the 2400 example, where MFP expects you to burn 2400 per day based on stats & activity level stated. MFP can't really process that you burn less in some hours (like while sleeping, or working a desk job), and more in others like when you're running errands or such. So MFP assumes every hour is 100 as there are 24 hours in day.

Lets say your BMR is 1800 which boils down to 75/hour.
• You wake up at 6am, sync Fitbit. You're at 75*6 or 450 calories burned because you were in bed/no activity since midnight. MFP thinks you should be at 600, so you'd have a 0 or -150 adjustment if you have negatives enabled.
• Then you do morning stuff. Shower, move around the house. At 7am Fitbit says you're at 540 burned. MFP thinks you should be at 700, so now its a -160.
• You go for a run and at 8am Fitbit shows you are at 900. MFP expected 800, so now you have a +100 adjustment.
• And the day goes on. Each time you sync, MFP compares your burn from Fitbit to its own estimation.

It can be helpful to look at your past total daily burns in Fitbit to have an idea of what is normal for you. And factor this into your daily meal planning. I know how much activity I need to do in order to end the day between 1900-2000 total burned calories. And some days I know that I won't be that active, and will only be 1700-1800. I eat accordingly.


Now lets say you log 250 cals of swimming into MFP from 2pm-2:30pm. First MFP will NOT doublecount. It will consider your logged info for that time period and ignore any 'calorie burn' from Fitbit for the same time. But it will add the 250 to the 2400 it expected you to burn. So now to get a Fitbit adjustment, your Fitbit would need to show you've burned 2650 calories in the day. So logging exercise in MFP will lower your Fitbit adjustment. Because if you log the exercise in Fitbit, and Fitbit uses that info and what it tracked to say you burned 2600, you'll see a +200 adjustment on MFP. If you log it in MFP, *I Think* Fitbit will pull it into your cals from MFP (have not done this in a while) and still show you burned 2600 total. But since MFP expected you to burn 2400 + 250, you'll see a -50. Either way, the end result is still that you burned 2600 so its not terribly important.

ritzvin

If you logged the swim in MFP rather than whatever server Fitbit goes to, and Fitbit had no way of measuring your workout (as in you weren't wearing a heart rate monitor since most don't work underwater) then Fitbit's estimate of your daily burned calorie total won't include it, and it will adjust MFP to negate the swim you logged there. (At least this is how the adjustment works with Garmin- I'm guessing Fitbit is similar). If you regularly do workouts that can't be measured by Fitbit and your activity level is set to sedentary (ie work a desk job), then you may want to disable negative adjustments and log them on MFP.

butterflyfaerie

RunRutheeRun wrote: »

There is a dedicated Fitbit group here but I'll tell ya anyway
Log your food only on MFP and your exercise on Fitbit, which will sync and adjust your total calories burned on MFP.

Have you changed the MFP settings to 'enable negative adjustments' and what activity level have you set MFP to?

What happened for you the other day is normal, Fitbit would have given you a burn for your activity but since you logged it yourself it then took it off so you weren't doubly posting.

Thanks! Have joined the group now

And thanks to StaciMarie1974 and ritzvin for the explanations!