difference in tdee calculators

ohnstadk
ohnstadk Posts: 143 Member
in Health and Weight Loss
Hello, first thanks for taking time to read this, and I apologize in advance if this is a little confusing. I have been on myfitnesspal for a few months now and am just wanting to make sure I am doing this right and eating enough, but still losing weight.

My fitness pal has me at a little more then 1600 for my daily caloric goal (before exercise) and after reading forums I thought that it might be a little low so I decided to take MFPals advice at calculate my tdee, but they come up with different results and I was wondering which is more accurate.

Things to keep in mind: I am female, 5'8 and 255 pounds. I am moderately active, and have MFP set to reflect that much. My body fat is 43%. And I exercise 4-5 times a week.

There are 4 different methods to calculate tdee on iifym.com.

The Mifflin -St joer has me at 3113 for tdee or 2335 at tdee -25%
The Enter Activity Level has me at 2897 for tdee (this bases it off of activity level as well)
The Harris-Benedict has me at 3464 for tdee, or 2771 at tdee-25%
Katch-McCardle has me at 2628 at tdee, or 2102 at tdee-25% (this bases of my body fat as well)

So my question is why do the numbers differ so much? Especially between the calulators and MFP? And which calculator is more accurate/should I use? Do the other calulators already enter gym workouts into the caloric levels? Any advice?

Again sorry if this is confusing. And thanks in advance for helping.

Replies

  • salvyhead
    salvyhead Posts: 66 Member
    From the way it's been explained to me - these so called calculators are 1) based on averages since calculating true TDEE is very expensive, requiring specialized apparatus and 2) each uses a different algorithm to estimate the TDEE based on somebody's study or research protocol.

    Don't fret too much - they provide AT BEST a guideline.

    If you plug my numbers in, for example, they say I can eat 2300 cal. a day and lose weight. That's a load of rubbish. If I ate 2300 I'd blow up like a balloon in the Macy's Parade. The way your actual body responds to actual calories is the true measure.

    -Sal
  • ohnstadk
    ohnstadk Posts: 143 Member
    Thanks for answering Sal.

    What would you then suggest I eat so that I am not starving myself, but am at a defict?
    Also are those calculators adding in exercise already or is that something I would still need to add.
  • heybales
    heybales Posts: 18,842 Member
    Harris and Mifflin (about 5% more accurate) BMR formulas are based on study participants at healthy weight, and average ratio of fat to non-fat (LBM) mass.

    As you go overweight, that ratio is rarely maintained - which means they are inflated for calorie burn.

    Take that inflated BMR times activity factor in TDEE scale, and now it's potentially really inflated compared to reality.

    Katch BMR is based on bodyfat %, but still average ratios of study folks.
    Which means when overweight it'll more slowly be underestimating your calorie burn, but not nearly as much as the others inflate it.

    So get a decent bodyfat%, at least with method within 5% accuracy normally, get the BMR, be truthful on activity level, and there is your average TDEE.

    Now take a 20% deficit off that amount and eat that daily.

    If you included planned exercise (3-5 hrs weekly) in the TDEE estimate, then exercise is already there, right?

    Here is means of using the best estimates all around.

    http://www.myfitnesspal.com/topics/show/813720-spreadsheet-bmr-tdee-deficit-macro-calcs-hrm-zones
  • aquinoz
    aquinoz Posts: 182 Member
    I'd use the katch-mccardle calculator because it's the most accurate. But just use the the calories it calculated for you as a guideline. For the most accurate results, try eating the amount of calories it gave you, to maintain, for a week and then weigh yourself at the end of the week to see if you've gained, maintained or lost weight. If you gained, decrease calories a bit and if you lost weight it's vice versa.

    It's just advice though...
  • ohnstadk
    ohnstadk Posts: 143 Member
    Harris and Mifflin (about 5% more accurate) BMR formulas are based on study participants at healthy weight, and average ratio of fat to non-fat (LBM) mass.

    As you go overweight, that ratio is rarely maintained - which means they are inflated for calorie burn.

    Take that inflated BMR times activity factor in TDEE scale, and now it's potentially really inflated compared to reality.

    Katch BMR is based on bodyfat %, but still average ratios of study folks.
    Which means when overweight it'll more slowly be underestimating your calorie burn, but not nearly as much as the others inflate it.

    So get a decent bodyfat%, at least with method within 5% accuracy normally, get the BMR, be truthful on activity level, and there is your average TDEE.

    Now take a 20% deficit off that amount and eat that daily.

    If you included planned exercise (3-5 hrs weekly) in the TDEE estimate, then exercise is already there, right?

    Here is means of using the best estimates all around.

    http://www.myfitnesspal.com/topics/show/813720-spreadsheet-bmr-tdee-deficit-macro-calcs-hrm-zones

    Thanks for the helpful information I didnt know that. As for the activity level ect. I am working out between 4 to 5 days a week, generally fluctuating between 4 and 5.

    I do the thirty minute circuit two to three times a week, with a trainer, and 30 minutes of cardio there after (Tuesday, Thursday, and about every other Saturday)

    I do cardio for 30 minutes and ab work outs (with a trainer) generally 20 minutes the other two days.

    But I am not sure what activity level that puts me at.
  • ohnstadk
    ohnstadk Posts: 143 Member
    I'd use the katch-mccardle calculator because it's the most accurate. But just use the the calories it calculated for you as a guideline. For the most accurate results, try eating the amount of calories it gave you, to maintain, for a week and then weigh yourself at the end of the week to see if you've gained, maintained or lost weight. If you gained, decrease calories a bit and if you lost weight it's vice versa.

    It's just advice though...

    That is definitely a good idea, but I am sort of gun shy about gaining any weight, since I need to lose weight to go into the career field I am attending school for.
  • LaurenAOK
    LaurenAOK Posts: 2,475 Member
    Since they're all estimates, I used an average of the four. For you, that's a TDEE of right around 3000 calories. Why don't you subtract 25% from that, try it for a month, and adjust from there? Unfortunately, a lot of this stuff ends up being trial and error.
  • heybales
    heybales Posts: 18,842 Member
    http://www.myfitnesspal.com/topics/show/813720-spreadsheet-bmr-tdee-deficit-macro-calcs-hrm-zones

    Thanks for the helpful information I didnt know that. As for the activity level ect. I am working out between 4 to 5 days a week, generally fluctuating between 4 and 5.

    I do the thirty minute circuit two to three times a week, with a trainer, and 30 minutes of cardio there after (Tuesday, Thursday, and about every other Saturday)

    I do cardio for 30 minutes and ab work outs (with a trainer) generally 20 minutes the other two days.

    But I am not sure what activity level that puts me at.

    Exactly - is 1 day or 1 hr of walking the same as 1 day or 1 hr of running as 1 day or 1 hr of lifting?
    No.

    That's why the spreadsheet is type and time of activity specific.

    Because 4-5 days will inflate your TDEE for sure.
  • salvyhead
    salvyhead Posts: 66 Member
    Hi again - just checking in. Was out all day and just saw your followup question - but it looks like you are in good hands with other MFPeeps who are much more knowledgable than I!

    Good luck.

    Sal

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