Does MFP account for increasing BMR or lowering BF%?

feefie04
feefie04 Posts: 67 Member
in Health and Weight Loss
I was mulling over my food diary and thought of a question.

Right now, with my current health and activity level, my goal cal is at 1500. What happens if I lose weight and exercise more, but my "general daily activity level" doesn't increase... Does MFP account for increased BMR via muscle gain? So theoretically if my body composition changes and I have less BF%, but weigh the same and general activity level stays the same (sedentary, lightly active, etc)... wouldn't I need to increase minimum daily calories above 1500?

I hope this comes across properly, if not maybe I can explain better once people respond. Thanks!

Edited to more properly form my question:
I'm interested in someone who weighs the same but one person has 10% BF and the other has 30%, with exactly the same daily activity level... wouldn't the BMR cals required be hugely different?

Replies

  • megleo818
    megleo818 Posts: 595 Member
    Excellent question -- I've been wondering the same (well, not about whether MFP makes adjustments, but if more fit means more calories). No, I don't have the answer, but I'll be watching to see if anyone else out there does! :happy:
  • GaidenJade
    GaidenJade Posts: 171
    Bump
  • ahviendha
    ahviendha Posts: 1,291 Member
    Well I'm not sure if it ups your calories based on BMR, but I know when I lose 15lbs (around that) it pings me and says "hey! you're lost a lot of weight recently! i'm gonna readjust your cals!" then it goes down 50-100 calories.
  • geekyjock76
    geekyjock76 Posts: 2,720 Member
    I custom entered everything so I didn't let MFP do anything. As you get leaner, and reduce body fat, you need to reduce the deficit by either: upping calories, reducing exercise, or both. Since most of your deficit should come from eating less, and you want to eventually eat at your adjusted maintenance, you should reduce the deficit mostly be upping calories. My activity level actually increases once I hit maintenance since I reinstate cardio.
  • yarwell
    yarwell Posts: 10,477 Member
    you were a bit self-contradictory by including both "What happens if I lose weight and..." and " I have less BF%, but weigh the same " but in essence MFP at best prompts you to re-run the calcs as you lose weight.

    As its BMR equation doesn't use %fat etc then if your weight is the same your MFP BMR is the same so you would need to do it manually via custom goals.
  • feefie04
    feefie04 Posts: 67 Member
    Excellent question -- I've been wondering the same (well, not about whether MFP makes adjustments, but if more fit means more calories). No, I don't have the answer, but I'll be watching to see if anyone else out there does! :happy:

    A lot of places say that more muscle % means higher BMR, because at rest muscle burns more than at rest fat.... I was just kind of wondering what BF% MFP uses as a baseline? Because my BF% is 30%, and that is neither normal or extremely huge, and I would think that my BMR would be affected by that number.

    Or is it negligible? is it give or take 200 cal based on BF% (anywhere from 10-50% BF), and being down by 500 a day is still within the adequate range for healthy weight loss?

    Theoretically if I was not eating my correct BMR for my muscle volume (which I don't have to worry about, but lets talk theory, lol) then I would be in danger of losing muscle mass as opposed to just fat, or would the fat come off faster? Or am I way off base?
  • feefie04
    feefie04 Posts: 67 Member
    you were a bit self-contradictory by including both "What happens if I lose weight and..." and " I have less BF%, but weigh the same " but in essence MFP at best prompts you to re-run the calcs as you lose weight.

    As its BMR equation doesn't use %fat etc then if your weight is the same your MFP BMR is the same so you would need to do it manually via custom goals.

    I guess I'm more interested in someone who weighs the same but one person has 10% BF and the other has 30%, with exactly the same daily activity level... wouldn't the BMR cals required be hugely different?
  • jamface11
    jamface11 Posts: 87
    I've been wondering, when going from sedentary to lightly active on fat2fit it gives me an extra 250calories a day. Does that mean I need to be exercising this much, or is this taking into account that the person should walk/stand more a day?
  • feefie04
    feefie04 Posts: 67 Member
    I've been wondering, when going from sedentary to lightly active on fat2fit it gives me an extra 250calories a day. Does that mean I need to be exercising this much, or is this taking into account that the person should walk/stand more a day?

    That means your daily activity level WITHOUT exercise is lightly active... which I assume is moderate standing/walking during the day.
  • yarwell
    yarwell Posts: 10,477 Member
    I guess I'm more interested in someone who weighs the same but one person has 10% BF and the other has 30%, with exactly the same daily activity level... wouldn't the BMR cals required be hugely different?

    Not according to the formula this site uses. Other formulae are available. They would differ.

    All of these things are line or curve fits to experimental data, some use age, height and weight (and gender) and others use lean body mass etc etc in their prediction equations. None catch more than 70% of people within +/- 10% of their estimates.

    The approach that fits your expectation is Katch-McArdle which works on the basis that a 350 lb woman is actually a 120 lb woman carrying 230 lbs of fat around, rather than a 350 lb superhuman body builder.

    http://www.calculatorpro.com/calculator/katch-mcardle-bmr-calculator/ uses % fat.
  • yarwell
    yarwell Posts: 10,477 Member
    I've been wondering, when going from sedentary to lightly active on fat2fit it gives me an extra 250calories a day. Does that mean I need to be exercising this much, or is this taking into account that the person should walk/stand more a day?
    It thinks your using 250 calories a day more than the other setting, however you achieve it. Most of humanity don't "exercise".
  • lambertj
    lambertj Posts: 675 Member
    Great question. A lower weight doesn't necessarily mean less calories if you have more muscle mass. With that being said, i've customized MFP diary
  • feefie04
    feefie04 Posts: 67 Member
    I guess I'm more interested in someone who weighs the same but one person has 10% BF and the other has 30%, with exactly the same daily activity level... wouldn't the BMR cals required be hugely different?

    Not according to the formula this site uses. Other formulae are available. They would differ.

    All of these things are line or curve fits to experimental data, some use age, height and weight (and gender) and others use lean body mass etc etc in their prediction equations. None catch more than 70% of people within +/- 10% of their estimates.

    The approach that fits your expectation is Katch-McArdle which works on the basis that a 350 lb woman is actually a 120 lb woman carrying 230 lbs of fat around, rather than a 350 lb superhuman body builder.

    http://www.calculatorpro.com/calculator/katch-mcardle-bmr-calculator/ uses % fat.

    Ok so my BMR req with the calculator was 1,535.91... so not too far off from MFP I guess, my daily req was set to 1500 to lose 1 lb per week with a lightly active daily level.


    But when I put in my daily requirement in the other calculator (http://www.calculatorpro.com/daily-calorie-calculator), it says my daily calories needed at sedentary is 1,867.83. (Now in order to lose weight, should I be going 500cal lower than this?)

    So, I guess that MFP isn't very far off for me, but I feel like I am in the statistically neutral range for users on the site... I wonder what would happen for people in the extremes?

    I am probably thinking too hard about this, but I think there's some piece of important information in there somewhere that I need to take into account at some point... (thanks, science intuition *sarcasm*)
  • yarwell
    yarwell Posts: 10,477 Member
    You are correct, it's the extremes where the differences become apparent.

    220 lb woman, 5'-2", age 30 - MFP says BMR=1671 calories/day "BMR based on the Mifflin - St. Jeor equations"

    Katch McArdle says BMR=1448 at 50% body fat or 1232 at 60% or 1663 at 40%

    Many of these equations were based on population groups such as conscripts in Mussolini's army before the second world war and the like. Always worth checking the sources.
  • treetop57
    treetop57 Posts: 1,578 Member
    From the MFP BMR calculator ( http://www.myfitnesspal.com/tools/bmr-calculator ):
    Our calculator uses the Mifflin-St. Jeor equations to estimate your BMR which is believed to be more accurate than the more commonly used Harris-Benedict equation.

    The Mifflin-St. Jeor equations use gender, weight, height, and age to estimate BMR. Percent body fat is not an input to that estimate. That's why BFP never asks you your body fat percentage. (Well, that and the fact that most people don't have an accurate measurement of their BF%.)

    So the answer to your question is "No, MFP does not account for increasing BMR with lower BF%."
  • Awkward30
    Awkward30 Posts: 1,927 Member
    Excellent question -- I've been wondering the same (well, not about whether MFP makes adjustments, but if more fit means more calories). No, I don't have the answer, but I'll be watching to see if anyone else out there does! :happy:

    A lot of places say that more muscle % means higher BMR, because at rest muscle burns more than at rest fat.... I was just kind of wondering what BF% MFP uses as a baseline? Because my BF% is 30%, and that is neither normal or extremely huge, and I would think that my BMR would be affected by that number.

    Or is it negligible? is it give or take 200 cal based on BF% (anywhere from 10-50% BF), and being down by 500 a day is still within the adequate range for healthy weight loss?

    Theoretically if I was not eating my correct BMR for my muscle volume (which I don't have to worry about, but lets talk theory, lol) then I would be in danger of losing muscle mass as opposed to just fat, or would the fat come off faster? Or am I way off base?

    While it's a good theoretical question, and the answer is that MFP only takes weight into consideration, so body fat percentage changes would not matter to their formula, it doesn't matter practically because the amount of calories in question would be minimal. I've gained 4 lb of muscle, and my BMR has changed by about 40 cals... and as a female, I can't expect to put on much more muscle without really really working for it. That is pretty negligible considering:
    1) It has been scientifically proven that people suck at accurately recording intake, people who are really bad can be off by 100%, nutritionists trying to do a good job can still be pretty off
    2) The equations are all for an average person, I may or may not be that average person. While there isn't a huge amount of individual variation, the 40 cals are well within the margin of error.

    That said, I pick my intake amount and adjust as I feel adjustments need to be made. MFP, you don't own me :)

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