# Why is MFP's calculation of BMR so much lower than other cal

Posts: 514 Member
I know there are different methods/formulae--how do they differ? Thoughts on which is best?
TIA!

## Replies

• Posts: 331 Member
I never noticed that. How much different is it?? I'm going to do a bit more research on that.
• Posts: 514 Member
As calculated by MFP using Mifflin-St.Joer mine is 1342
FitnessFrog: 1410
Fat2Fit using Harris-Benedict formula: 1416
Fat2Fit using the Katch-McArdle formula: 1421

So...not a gigantic difference, really, but enough to wonder about the differences. Acc to Fat2Fit the Katch-McArdle takes body fat percentage (which I calculated online and averaged with what my gym calcuated) into account...
• Posts: 31,634 Member
MFP's uses the mifflin st-jeor which is more accurate for 'modern' humans -- AKA its much more accurate for how sedentary most people in our modern civilization are.

The H-B calculation was based on humans from the early 1900s (men at that I believe) when people were fairly active both at work and at home - there wasn't a lot of the shortcut helpers we have available these days.

Er and by sedentary/active what I mean to imply is that muscle mass is higher for people who are active day-to-day.

Katch-McArdle takes lean body mass into the equation so if you know that its theoretically more accurate than the others.

but in the end these are ALL just based on averages across a sample size. They're a good starting point for figuring out how much you should eat but they aren't "true" -- just a guess based on data.
• Posts: 70
bump
• Posts: 329 Member
As calculated by MFP using Mifflin-St.Joer mine is 1342
FitnessFrog: 1410
Fat2Fit using Harris-Benedict formula: 1416
Fat2Fit using the Katch-McArdle formula: 1421

So...not a gigantic difference, really, but enough to wonder about the differences. Acc to Fat2Fit the Katch-McArdle takes body fat percentage (which I calculated online and averaged with what my gym calcuated) into account...
i was wandering this myself a while back. turns out the mifflin-st.joer is more accurate if bodyfat % is not known. so i use that standard now. the difference fo me is almost 200cal.
• Posts: 6,296 Member
Also, MFP has your deficit built in, so that even if you do no exercise, you'll still lose.

Some other calculators do not approach it that way.
• Posts: 31,634 Member
Also, MFP has your deficit built in, so that even if you do no exercise, you'll still lose.

Some other calculators do not approach it that way.

MFP isn't building a deficit into the BMR calculation though, it just uses one that's calibrated for a world where most people drive to work/errands, don't carry their groceries further than from the driveway to the house, and have jobs where at least half the day is spent in a chair
• Posts: 621 Member
MFP's auto settings are not the best. I use my TDEE and my BMR and eat in between that instead of 1200. I now eat 1500 minimum, PLUS my exercise calories. I never have net carbs under 1350