Katch-McArdle Formula vs. MFP

sugarandspice27

Ok so the Katch-McArdle Formula is 260 calories LESS than what MFP suggests.

I am: 5'7", 30 years old, 316 lbs, 59.3% Body Fat.

Katch-McArdle Formula:

Caloric Need:
Estimated Base BMR: 1639 Calories.
Estimated TDEE: 1967 Calories.
Estimated Daily Caloric Need For Weight Loss: 1467 Calories.

MFP suggests me to eat 1727 calories a day, a difference of 260 calories.

Exercise calories aside, can anyone shed some light on this? What do you make of it?

rainbowbow

The katch mcardle formula is I believe the most accurate as it takes bf into account. Assuming your bf% is correct.

Mind you these are all estimates!

sugarandspice27

I'm thinking about slowly tapering down my calories by 100 and see if I notice a difference.

hmbennington

I did this as well and MFP estimates about 140 higher per day. My thought it that I was WAY exceeding this prior so anything I can do to decrease what I used to eat is a plus and on my way a healthier me. :happy:

angelicarubi

interesting, not sure, but all I can say is you are doing an awesome job and losing a healthy amount of weight each week. So this system must be working for you:) keep up the great work!

yarwell

I was a bit confused by your first sentence, you might want to edit it ;-)

The K-M formula differs from MFP in its estimation of BMR. From then on the logic is probably the same, ie

multiply BMR by 1.2 to estimate total daily (sedentary) energy use
subtract 500 calories from this to give 1 pound/week target loss

Hence 1639 * 1.2 - 500 = 1467

MFP : 1856 * 1.2 - 500 = 1727 (assuming you told MFP 1 pound per week loss)

The BMR figures are estimates, and so is the 1.2 factor for sedentary activity. All of them could be out so pick the one you fancy and give it a run for a month. If no loss then revise downwards. I you do additional exercise you can eat an equivalent amount of calories to maintain the above loss rate, or eat some of them to increase the rate.

sugarandspice27

I was a bit confused by your first sentence, you might want to edit it ;-)

The K-M formula differs from MFP in its estimation of BMR. From then on the logic is probably the same, ie

multiply BMR by 1.2 to estimate total daily (sedentary) energy use
subtract 500 calories from this to give 1 pound/week target loss

Hence 1639 * 1.2 - 500 = 1467

MFP : 1856 * 1.2 - 500 = 1727 (assuming you told MFP 1 pound per week loss)

The BMR figures are estimates, and so is the 1.2 factor for sedentary activity. All of them could be out so pick the one you fancy and give it a run for a month. If no loss then revise downwards. I you do additional exercise you can eat an equivalent amount of calories to maintain the above loss rate, or eat some of them to increase the rate.

Oops! Fixed it.

No, I told MFP I wanted to lose 2lbs a week...

sugarandspice27

BUMP

rileysowner

Eating at the lower number is not necessarily better. I would say just stick with MFP's numbers unless you are having huge issues losing.

yarwell

No, I told MFP I wanted to lose 2lbs a week...

Oops. In that case it'll be subtracting 1,000

BMR based on the Mifflin - St. Jeor equations by MFP is 2,186

2,186 * 1.25 - 1000 = 1732 <- sound better ?

That is rather a big difference in BMR. MFP is aiming for twice the loss rate yet has more calories.

SteveTries

I'm thinking about slowly tapering down my calories by 100 and see if I notice a difference.

This is the answer

All the different formulas are estimates, nothing more. Not one of them is accurate for everyone and you'll drive yourself nuts trying to track down the "most" accurate.

Given that nutritional values aren't 100% accurate either it's just not worth the effort.

Pick one, use that as a baseline, observe-adjust-repeat

yarwell

I looked a bit harder at this. With a BMI approaching 50 it would be fair to say that most of the equations for BMR etc will not have had many if any subjects similar to yourself in their development., so there's a high chance the correlations will be way out - the data used is often quite old (Italian Fascist conscripts in one case) etc.

The equations are :-

Mifflin-St Jeor female 9.99*Weight + 6.25*Height – 4.92*Age -161
Katch-McArdle N/A 370 + 21.6*LBM

One paper http://www.ajcn.org/content/49/1/93.full.pdf reports a RMR of 30 +/- 2 kcal/day per kg of fat free mass, which in your case with 58.4 kg of FFM would be a range of 1635 to 1868 calories per day. This is on similar people to yourself.

An Italian study came up with its own equations based on a population of larger ladies :
REE=FFMx0.067+FMx0.046+1.568 = 2263 cals/day (equation is in MJ)
REE=Weightx0.042+Heightx3.619-2.678 = 2274 cals/day (again. equation is metric)

REE is resting energy expenditure.

The Italian and a Belgian study also recommended the Siervo equation as most accurate for larger women, but I can't find that !

sugarandspice27

I looked a bit harder at this. With a BMI approaching 50 it would be fair to say that most of the equations for BMR etc will not have had many if any subjects similar to yourself in their development., so there's a high chance the correlations will be way out - the data used is often quite old (Italian Fascist conscripts in one case) etc.

The equations are :-

Mifflin-St Jeor female 9.99*Weight + 6.25*Height – 4.92*Age -161
Katch-McArdle N/A 370 + 21.6*LBM

One paper http://www.ajcn.org/content/49/1/93.full.pdf reports a RMR of 30 +/- 2 kcal/day per kg of fat free mass, which in your case with 58.4 kg of FFM would be a range of 1635 to 1868 calories per day. This is on similar people to yourself.

An Italian study came up with its own equations based on a population of larger ladies :
REE=FFMx0.067+FMx0.046+1.568 = 2263 cals/day (equation is in MJ)
REE=Weightx0.042+Heightx3.619-2.678 = 2274 cals/day (again. equation is metric)

REE is resting energy expenditure.

The Italian and a Belgian study also recommended the Siervo equation as most accurate for larger women, but I can't find that !

This post left me far more confused than I was before!

leopard_barbie

It's so hard knowing which ones to go with! I tried measuring BF% using various websites & got the same massively differing results (21% which I know is way too low-37.5%).

I know it's all trial & error but it's so tempting to stick with the neat little 1200 calories MFP recommends...

RAEQ127

I recently discovered the Katch-McArdle formula and there was a 561 calorie difference between that and MFP. I've lowered my calories and so now i hope that makes me start losing again.

davidindenver

The challenge with any formula is that they can't account for variables, such as thyroid issues, digestive issues, the effects of medications, etc.

To get a scientific measurement of your Resting Metabolic Rate, you can get tested using a BodyGem or MedGem indirect calorimeter. It only takes 5-10 minutes for it to determine your RMR.

You can link to metabolicratetest dot com and plug in your zip code to find a local measurement provider. The link is on the bottom right of the page.

And you can get more information on the BodyGem or MedGem indirect calorimeters, if you're a Personal Trainer or Dietitian who wants to provide RMR measurements.

HenricProjects

I well understand, that I am about 5 years late.
Still for those whom stumble on the topic.

Mifflin St Jeor is best to use for a generic anybody, regardless their body fat percentage.
If you already have a lean body complex, say a body fat percentage below 15%, than the Katch-McArdle is best to use.
As you do not want to feed your already low body fat percentage.

E.g., for me, in metric units:
Age 67 [in 2018]
Weight 78,5 kgs
Body fat 11,1%
BMR circa 1.870 kcal [for the K-M formula] which keeps me on track.

While Mifflin St Jeor calculates 1.600 kcal, which [when also corrected for the cals used] lowers my weight.

Trust this helps those looking for the best formula to utilize. Mifflin St Jeor the best for loosing weight.

PAV8888

HenricProjects wrote: »

I well understand, that I am about 5 years late.
Still for those whom stumble on the topic.

Mifflin St Jeor is best to use for a generic anybody, regardless their body fat percentage.
If you already have a lean body complex, say a body fat percentage below 15%, than the Katch-McArdle is best to use.
As you do not want to feed your already low body fat percentage.

E.g., for me, in metric units:
Age 67 [in 2018]
Weight 78,5 kgs
Body fat 11,1%
BMR circa 1.870 kcal [for the K-M formula] which keeps me on track.

While Mifflin St Jeor calculates 1.600 kcal, which [when also corrected for the cals used] lowers my weight.

Trust this helps those looking for the best formula to utilize. Mifflin St Jeor the best for loosing weight.

Actually the debate as to which formula is the most accurate for which population is still raging.

MFP is using Mifflin. But this necro thread also has other errors.

MFP sedentary is an activity factor of 1.25, not the 1.2 that they were using, and includes approximately 30 minutes of activity/your first 3500 steps a day. Lightly active, active, very active on MFP are set as AF of 1.4, 1.6, and 1.8 respectively. People who are actively working on their feet all day can easily come in above 1.8.

In the original post the KM derived calories to lose weight are set at -500 of TDEE. But the user was setting MFP to -1000 of sedentary and was not considering that MFP uses NEAT, therefore exercise would have to be added after the fact.

Anyway, neither Katch or Mifflin are "perfect" for class II and III obese.

https://www.ncbi.nlm.nih.gov/pubmed/11817239

https://onlinelibrary.wiley.com/doi/full/10.1038/oby.2010.326

Having said all that...

Estimators estimate.... and real life lets you adjust!

you plugz your numbers in MFP.

you pickz a REASONABLE goal (2lbs a week is NOT for everyone. Almost invariably it is too fast for most people who are not high overweight or obese. And it could be too slow for someone who is class III and active.)

you logz your foodz and activities as accurately as you can.

you plotz your weight changes in a trending weight app or web site.

You lookz at your results in 4 to 6 weeks.

You adjustz based on your actual results!

EZ-Peazy!

nowine4me

Honestly, just pick a horse. You’ll have your own data soon enough. She who can lose on the most calories wins.