Discrepancy in calorie allotment from MFP and IIFYM to lose weight at the same rate (1 lb a week)

Ruedora
Ruedora Posts: 15 Member
in Health and Weight Loss
I have been seeing a lot of posts where people mention TDEE and IIFYM so I figured I would check it out. I entered in all of my information and there was a pretty significant difference between the calories that MFP gives me and what the IIFYM spit out (about 300 a day). Has this happened for anyone else? Which do you follow?

Replies

  • kgeyser
    kgeyser Posts: 22,505 Member
    MFP does not include exercise calories and expects you to eat your exercise calories back. IIFYM takes exercise into account when calculating the calorie goal. Hence the discrepancy.
  • rainbowbow
    rainbowbow Posts: 7,490 Member
    What do you mean by the iifym "spitting out 300 a day"?

    Are you using a specific site other than MFP?

    Please clarify so we can help!
  • funchords
    funchords Posts: 413 Member
    kgeyser wrote: »
    MFP does not include exercise calories and expects you to eat your exercise calories back. IIFYM takes exercise into account when calculating the calorie goal. Hence the discrepancy.
    This is correct.

  • Ready2Rock206
    Ready2Rock206 Posts: 9,487 Member
    Ruedora wrote: »
    I have been seeing a lot of posts where people mention TDEE and IIFYM so I figured I would check it out. I entered in all of my information and there was a pretty significant difference between the calories that MFP gives me and what the IIFYM spit out (about 300 a day). Has this happened for anyone else? Which do you follow?

    Wouldn't take too much exercise to get to the 300 a day difference - so they're pretty much the same. I'd try the IIFYM number and if after a month you're not losing then drop it 100 or so calories and go from there.
  • Ruedora
    Ruedora Posts: 15 Member
    edited November 2014
    rainbowbow wrote: »
    What do you mean by the iifym "spitting out 300 a day"?

    Are you using a specific site other than MFP?

    Please clarify so we can help!

    I went to www.iifym.com and used the calculator there. The calculator gave me calorie number that was 300cal/day different than MFP.



  • Ruedora
    Ruedora Posts: 15 Member
    edited November 2014
    kgeyser wrote: »
    MFP does not include exercise calories and expects you to eat your exercise calories back. IIFYM takes exercise into account when calculating the calorie goal. Hence the discrepancy.


    Thank you! Makes perfect sense :smile:



  • Ruedora
    Ruedora Posts: 15 Member
    Ready2Rock206 wrote: »
    Ruedora wrote: »
    I have been seeing a lot of posts where people mention TDEE and IIFYM so I figured I would check it out. I entered in all of my information and there was a pretty significant difference between the calories that MFP gives me and what the IIFYM spit out (about 300 a day). Has this happened for anyone else? Which do you follow?

    Wouldn't take too much exercise to get to the 300 a day difference - so they're pretty much the same. I'd try the IIFYM number and if after a month you're not losing then drop it 100 or so calories and go from there.

    That's good advice. I will try that.

    Thank you :smile:
  • rainbowbow
    rainbowbow Posts: 7,490 Member
    edited November 2014
    Ruedora wrote: »
    rainbowbow wrote: »
    What do you mean by the iifym "spitting out 300 a day"?

    Are you using a specific site other than MFP?

    Please clarify so we can help!

    I went to www.iifym.com and used the calculator there.




    Ah, okay. Wanted to make sure. Both iifym and mfp have the option to set your activity level so those need to match. To the others saying mfp doesn't inc exercise, that depends on how you set it up. If you select active, lightly active, etc. to include your weekly workouts it does.

    The difference is likely in the "15-20-25%" deficit it does. Mfp calculates weight loss not by "percentage of deficit" but by "pounds to lose".

    The difference would be EX.

    Maintain: 2,000 calories
    Iifym deficit 20%= gives you 1600 calories
    Mfp deficit 1 pound per week= gives you 1500 calories

    So mfp will always give you a deficit based on 500 calories= 1lb weight loss. IIFYM gives you a deficit based on the percentage of your TDEE.

    Hope this helps!
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  • Ruedora
    Ruedora Posts: 15 Member
    rainbowbow wrote: »
    Ruedora wrote: »
    rainbowbow wrote: »
    What do you mean by the iifym "spitting out 300 a day"?

    Are you using a specific site other than MFP?

    Please clarify so we can help!

    I went to www.iifym.com and used the calculator there.




    Ah, okay. Wanted to make sure. Both iifym and mfp have the option to set your activity level so those need to match. To the others saying mfp doesn't inc exercise, that depends on how you set it up. If you select active, lightly active, etc. to include your weekly workouts it does.

    The difference is likely in the "15-20-25%" deficit it does. Mfp calculates weight loss not by "percentage of deficit" but by "pounds to lose".

    The difference would be EX.

    Maintain: 2,000 calories
    Iifym deficit 20%= gives you 1600 calories
    Mfp deficit 1 pound per week= gives you 1500 calories

    So mfp will always give you a deficit based on 500 calories= 1lb weight loss. IIFYM gives you a deficit based on the percentage of your TDEE.

    Hope this helps!

    Ah yes. this is great. Looking at them both I can see that what I entered for activity level here and what I entered in on IIFYM is different.

    Everyone has been so helpful. I'm glad I asked.

    Thank you for your reply :smile:
  • rainbowbow
    rainbowbow Posts: 7,490 Member
    edited November 2014
    TastesLikeBurning wrote: »
    I'm sorry if this is a stupid question that I probably should already know the answer to, but IIFYM already calculates your exercise included into your daily calories. So it is assuming that every time you exercise, you will burn a set amount of calories?

    Yes. It assumes that you burn 35% more (if you select 3x a week) than your BMR. It adds on 5% for each additional day you select.

    Edit: said body weight, meant BMR. :)
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