Exercise calorie question.

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Bella77007
Bella77007 Posts: 78 Member
in Goal: Maintaining Weight
I have been tweaking my calories trying to maintain, MFP says that as a sedentary female weighing 102.3 pounds and being 5 ft 1 (156cm so close enough) I should eat 1350, fitbit gives me 1295 if I do very little, anyway I was still losing on 1350 so I increased by 100 per day and problem was sorted.

But I am enjoying being more active now, the fitbit has motivated me a lot and whilst I am far from being intense with exercise most days I am earning about 300 extra calories.

So two questions really:

One is that for some reason my exercise calories drop as the day goes on, I must be misunderstanding how this works, for example today I had finished logging food and went for a jog, it said I had earned 351 calories but I just picked up my phone and it's now saying my exercise calories are 287 so in the past 5 hours I have 'lost' some exercise calories, why is this? I have not added more food.

Second question:

I know that in general exercise calories are often generous anyway so would it be sensible to only eat back half and see how I get on with that?

Many thanks :)

Replies

  • bonniejo
    bonniejo Posts: 787 Member
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    What I prefer to use is an average over time instead of a day-to-day fluctuation, because fitbit's calorie calculations are funny. They seem to assume that you will continue to be active until midnight, which is not true most of the time. So possibly try using the 7 day average on fitbit to set your calories, eat at that and see what happens after about 2 weeks.
  • BeYouTiful94
    BeYouTiful94 Posts: 289 Member
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    For the first question, Fitbit does a "real-time" (for lack of better wording) caloric measurement, while MFP does a daily caloric measurement. MFP syncs with Fitbit and uses the steps and some forumula or another to bring the Fitbit number up to a daily number. If that number is more than what MFP has for your daily number, you get an addition and vice versa. After you exercise and ramp up your steps, the MFP formula uses those steps to calculate your daily calories from that point in time. If you don't move much over the next couple of hours, the adjustment goes down because the estimate goes down. So if you had, say 7500 steps at 8 am, MFP would sync with Fitbit and give you an insanely high adjustment, whereas if you had 7500 steps at 5pm, MFP would sync with Fitbit and give you maybe 150 calories.
  • autumnblade75
    autumnblade75 Posts: 1,660 Member
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    The difference seems to be less the lower you set your activity level on MFP. I have my level set to Sedentary even though that means my exercise calories are sometimes more than my daily calorie goal.

    When I had my activity level set to Very Active, I would lose enough calories between 5pm and midnight to come back in the morning and look at the previous day and I would be over my goal. Now, I lose fewer than 70 calories in the evening and I don't lose my entire deficit, even when I am very close to my goal number.
  • Owlfan88
    Owlfan88 Posts: 187 Member
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    Somehow my Fitbit and MFP together don't work this way. I had negative calories around 11 pm last night (but small, like -11). I walked upstairs, brushed teeth, got ready for bed. Nothing strenuous. I was figuring I might break even or be less negative this morning, but I had +41 calories left this morning. I'm not complaining! But it seems different to how most people seem to find it. BTW, I have my level set to lightly active, though I usually earn hundreds of extra calories on a walk each day.
  • Bella77007
    Bella77007 Posts: 78 Member
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    Thanks everyone, I understand it now :)

    I have MFP set to sedentary and then see what fitbit adds, I haven't actually been eating back any calories from exercise yet and it's too soon to know if I need to based on weight changes but obviously if I stay more active and start dropping again I will eat some back, I was just a bit confused about why it dropped the amount as the day went on but that makes total sense now.
  • LivingtheLeanDream
    LivingtheLeanDream Posts: 13,342 Member
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    Your Fitbit and MFP adjust as the day goes on, if you exercise in the morning MFP just assumes you'll be as active the remainder of the day, but if you aren't then thats why calorie burn is adjusted down on MFP.
    Look at your numbers near the end of the day, thats your TDEE. Eat near those given calories and you will maintain. Fitbit is pretty accurate I find :smile:
  • Bella77007
    Bella77007 Posts: 78 Member
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    Thank you, I was so confused with it all at first but it's starting to make a lot of sense now, I note that on an average day when I check before bed it is around the 1600-1650 mark, MFP said 1350 and I am on maintaining on 1450 at the moment.

    I only recently became more active so I'm not sure how my weight will go quite yet, I will track for a couple of weeks and adjust accordingly if it drops again, at 5 ft 1 being 102-ish isn't a problem but I don't really want to go much lower and exercise is addictive :)

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