Fit 2 Fat calculator is confusing...

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SlytherinPrefect
SlytherinPrefect Posts: 64 Member
in Health and Weight Loss
This is what the Fat2Fit calculator says for me:
Harris-Benedict Formula

There are a few different methods to calculating yourbasal metabolic rate (BMR). One of the most popular, developed in the early 1900's is called the Harris-Benedict formula. Based on this formula, your current BMR is 1545 calories.


Katch-McArdle Forumla

The numbers above are fairly accurate, however they don't take into account your lean body mass. A more accurate formula that does take your lean body mass into account is the Katch-McArdle formula. Since many of us have scales that will tell us our current body fat, this formula may yield more accurate results. Based on the information you provided, body fat percentage of 45%, you have a lean body mass of 93 lbs., and your BMR is 1283 calories.

How Many Calories Should I Eat?


Activity Level | Daily Calories
Lightly Active (light exercise/sports 1-3 days/wk) | 2124

Is the "How Many Calories" part calculated based on the 1545 or the 1283?

Ultimately, should I be using the 1283 and doing the TDEE math based on that?

ETA: Link - http://www.fat2fitradio.com/tools/bmr/

Replies

  • Zelinna
    Zelinna Posts: 207 Member
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    I believe the "how many" is based upon your goal weight and not on your BRM. Basically, it is as if you put your goal weight as your current weight on MFP and ate to maintain that weight.

    The way I understand this site to work is that if you eat at the calories for your goal weight you will eventually get there. No other calculations needed.

    I did loosely follow this for a while, until I got close to maintenance. I set my daily goal as my bmr and then ate back my exercise calories. It worked for me.
  • SlytherinPrefect
    SlytherinPrefect Posts: 64 Member
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    UGH. I obviously meant "Fat 2 Fit".

    I put in my *current* weight in both areas so I could figure out my TDEE (and my deficit) on my own. I'm just confused as to which BMR to use to start those calculations.
  • Mokey41
    Mokey41 Posts: 5,769 Member
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    The 1200 one since you supplied a BF%. You carry a large percentage of fat so you don't need to feed it. You want to feed your lean body mass.
  • SlytherinPrefect
    SlytherinPrefect Posts: 64 Member
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    Thanks, Mokey. I figured that was the case. Guess I'm at maintenance for today - I'll fix it for tomorrow.
  • astange83
    astange83 Posts: 105
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    1699 is TDEE (2124)-20%. BMR is what your body needs to survive doing nothing all day.
  • SlytherinPrefect
    SlytherinPrefect Posts: 64 Member
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    Yeah, but if the 2124 is based off of the less-accurate 1500+ BMR as I listed above, then it's still wrong. Also, it's at maintenance levels.
  • SlytherinPrefect
    SlytherinPrefect Posts: 64 Member
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    Sigh - more confusion. Calculator here (http://iifym.com/tdee-calculator/) gives same BMR: 1283. Gives TDEE as 2100. 20% cut would be 1680

    So how do I log that in MFP so I can still count my exercise cals? Should I be trying to do 1680 consumption no matter what my exercise is? I only usually burn 120-150 cals a day at my current level of working out. So should my MFP goal be, say 1530 to NET?

    Advice?
  • shadow2soul
    shadow2soul Posts: 7,692 Member
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    If you want to try the TDEE method:

    Set a custom Goal of 1680
    Then either:
    A) Log exercise with only 1 calorie burn
    or
    B) Don't log exercise at all

    The 1680 calories per day already takes into account your exercise.
  • 141by2016
    141by2016 Posts: 179
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    Either follow MPF's recommendation (but not less than your BMR - probably around 1350) and eat back your exercise calories OR TDEE -20% no matter what (exercise is already counted). Thems' the rules.
  • Mokey41
    Mokey41 Posts: 5,769 Member
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    You may not want to share all your stats but I'm finding it hard to believe your BMR is really that low. I'm old and small and mine is 1194. You appear much younger than I am and if your ticker is right much heavier. I can't see how there would only be a hundred calorie difference there.

    If you post your stats someone could probably give you some help with figuring this all out.
  • SlytherinPrefect
    SlytherinPrefect Posts: 64 Member
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    Age: 31
    Height: 5'4"
    Weight: 168 lbs
    Neck: 14.3"
    Waist (smallest): 34"
    Waist (bellybutton): 39.5"
    Hips: 43.5"
    Chest: 42"

    According to F2F: body fat - 39.1% (I did it wrong yesterday - I read too quickly and used my navel measurement instead of my smallest measurement)

    So, new stats - using their BMR calculator with the following:

    Your age: 31
    Choose your sex: female
    Your height (in inches): 64
    Your CURRENT weight (in pounds): 169 (yesterday)
    Your GOAL weight (in pounds): 169 (yesterday) - again, to check what my actual BMR etc is to do the math myself.
    Your body fat percentage (if known): 39.1%

    Output (100 cals more or so):
    Custom BMR Calculation
    Thanks for checking your BMR here on Fat 2 Fit Radio. If you're not already subscribed to Fat 2 Fit Radio, consider doing so today. Please visit the Subscribe page to get the podcast delivered automatically to your iTunes, Juice, e-mail inbox or the podcatcher of your choice for FREE.

    Entered information: 31 year old female, 64 inches tall, weighing 169 pounds, BMI of 29 (Overweight).

    From the information that you entered, you'd like to weigh 169 lbs.


    Harris-Benedict Formula

    There are a few different methods to calculating yourbasal metabolic rate (BMR). One of the most popular, developed in the early 1900's is called the Harris-Benedict formula. Based on this formula, your current BMR is 1545 calories.


    Katch-McArdle Forumla

    The numbers above are fairly accurate, however they don't take into account your lean body mass. A more accurate formula that does take your lean body mass into account is the Katch-McArdle formula. Since many of us have scales that will tell us our current body fat, this formula may yield more accurate results. Based on the information you provided, body fat percentage of 39.1%, you have a lean body mass of 103 lbs., and your BMR is 1381 calories.


    How Many Calories Should I Eat?

    Based on your goal weight, the following chart was generated. The chart shows the number of calories that you should eat on a daily basis to reach your goal weight. At Fat 2 Fit Radio we advocate eating like the thin, healthy person that you want to become. The calorie levels you see in the chart are not extreme, but they do create that all important caloric deficit that is required to get you to your goal weight in a safe manner. Once you reach your goal weight, you will continue eating the same number of calories for the rest of your life to maintain that weight. You'll never be on a diet again.

    Based on how much activity you do on an average day, the calories in the right column will be the number of calories that you will be able to eat at your goal weight. If you start eating those calories right now (eating like the thinner you), you will eventually become that thinner person. As you get closer to your goal weight, your weight loss will start to slow down. It is OK to eat a few hundred calories less per day (200-300) to speed up your weight loss at this point.

    Activity Level Daily Calories
    Sedentary (little or no exercise, desk job) 1854
    Lightly Active (light exercise/sports 1-3 days/wk) 2124
    Moderately Active (moderate exercise/sports 3-5 days/wk) 2395
    Very Active (hard exercise/sports 6-7 days/wk) 2665
    Extremely Active (hard daily exercise/sports & physical job or 2X day training, i.e marathon, contest etc.) 2936
  • SlytherinPrefect
    SlytherinPrefect Posts: 64 Member
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    Updated results from IIFYM w/ new body fat %:

    Your BMR is: 1382 Calories/Day
    Your TDEE is: 2263 Calories/Day (for exercising every day - but does 20 minutes of walking count?)
  • SlytherinPrefect
    SlytherinPrefect Posts: 64 Member
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    Here's a further example:

    If I did nothing - sedentary desk job, my stats would be (according to IIFYM):

    BMR: 1382
    TDEE: 1659

    That means if I did nothing at all, I'd need an additional ~300 calories a day to maintain and sit there.
    When I exercise (20 minutes of walking a day right now while I'm recouping from a knee problem), I burn at most 150 calories a day.

    So is my TDEE really 1800? Because it's my *completely sedentary* TDEE + the workouts I do? And then I should eat at a 20% cut from that?

    This is how the math is working out at my head. I don't care how much I end up needing to eat - I'm not afraid of more calories. I just don't want to go, "Woo, now I can eat 2000 calories!" and be eating 400 more than I should be every day - defeats the purpose of doing the math in the first place.
  • Rays_Wife
    Rays_Wife Posts: 1,173 Member
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    Wow. After being on MFP for almost 2 years, your question has blown my mind. I thought I knew all about TDEE and BMR but I think you have a great point. Do estimated TDEE numbers get more inaccurate the higher BF% a person has? Like Mokey said there is no need to "feed the fat". I went over to scooby workshop and based on my estimated BF of 50-65% (Katch Mcardle) my TDEE would actually be 400-700 calories lower than I originally calculated with the Harris-Benedict formula!

    I am SO. CONFUSED. This may explain why I haven't lost weight eating at these numbers for awhile now. I hope you get answers to your question , I will be watching this thread!
  • SlytherinPrefect
    SlytherinPrefect Posts: 64 Member
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    I reposted the entire question in novel form over on EM2WL here, maybe I'll get someone who's got an idea of what I'm getting at!

    Here's the link to that post: http://www.myfitnesspal.com/topics/show/1115545-this-is-a-novel-understanding-my-tdee

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