Had my RMR tested a second time and now confused

husseycd Posts: 814 Member
So I had my RMR tested yesterday morning for the second time and it came out to be 1300. This was first thing in the morning before food, coffee, 12 hours after exercise, etc. And now I'm confused but I'm not sure if I should be.

When I had it tested 1.5 years ago or so, I did the same machine only at lunch time. So I certainly wasn't as "empty". I'm not even sure I prepped correctly for it. I don't think I'd had lunch, but I'd certainly had breakfast and coffee. That time it came out to 1560, which was a higher than expected, but seemed to match with other calculations (see below).

I also had my bodyfat tested back in March with a BodPod and got 18.9%. If I use Katch-McArdle using body fat, I get a BMR of 1407. Since RMR is supposed to be higher than BMR, that leads me to believe my number of 1300 is low. However, my BodPod results gave me a calculated RMR of 1307.

So, I know RMR is supposed to be higher than BMR. This isn't necessarily well documented on the Internet. One site I looked up indicated that the Mifflin equation is closest to RMR. http://www.caloriesperhour.com/tutorial_BMR.php When I plug those number in, I do indeed get very close to 1300.

I also have a BodyMedia. And everything I've seen puts the multipliers on my activity level (very active) close to when I'm very active with the BodyMedia using the 1300 number. When resting during the test, my BodyMedia had me at 0.9 cal/min, which calculates to a RMR of 1296. That tells me the BodyMedia is spot on.

This all came up because I'm cutting for Halloween before I start my bulk on Nov. 1st, and I want the most accurate numbers. And I'm impatient. I'm also an engineer by trade so I'm a number/spreadsheet geek. For the last three weeks, I've cut my calories, but gained "weight". BodyMedia has me at an average daily deficit of 300 calories, so I should have dropped a few lbs. I went from 128.5 on Sept 11 to 130.7 today. Where I should be clocking in closer to 127 if the numbers are accurate. I know water weight can mask true weight loss, and my measurements seem smaller (it's so hard to tell in 3 weeks), but this whole different RMR has kinda freaked me out.

Because...for the last year or so, in order to maintain my weight, I eat at a deficit M-Th, and then have refeeds on Friday-Sunday. I'm not great at counting calories on those days. When I do, I'm usually over maintenance by 500-1000 calories. I've been better about counting on weekends, but I still tend to estimate, unlike during the week where I weigh/measure everything. Since I've been doing this for over a year, I'm pretty positive I'm consuming less on the weekends than before the cut, but I can't be 100% sure since I'm not weighing. I have dropped my cals during the week to ~1600. Though thiis last week I've been closer to 1700. My diary is open. And yes, I like to drink. :drinker:

So that was super long, but I wanted to get some opinions. Is my 1300 rested & fasted RMR an okay number? Or does it seem low? I'm probably due for a diet break, but technically, I get one every weekend, so I'm not sure that's necessary.

Stats: 38 year old female, 130.7 lbs (as of this morning), Bodyfat 18.9%, 5'5".

I do have another BodPod test scheduled for next Tuesday, so we'll see if that 18.9% has changed.


  • heybales
    heybales Posts: 18,842 Member
    Bodpod results I've found from asking, including my own, use the Nelson RMR formula, and researching that it usually comes in low compared to measured and other RMR formula's. So it may be close to a BMR estimate actually, though it's clearly used as RMR formula in studies.

    What is the Cunningham RMR using your BF% results? That one seemed to have best reviews.
    If you have used my spreadsheet, that result from your entered stats on Simple Setup tab is on the Fitbit_BodyMedia tab.
    If not, formula is:
    (22 x LBM in kg) + 500

    Now how does that compare to the RMR test?
    Is test within 5% of that value?
    Spreadsheet on Simple Setup tab where you enter in tested RMR will also tell you if within 5% of estimate using BF% stat you entered..
    Yes, I tried to think of everything.

    And yeah, lunch time visit totally invalid RMR test, you were outputting more CO2 based on digesting food from breakfast, which would appear you were burning more oxygen (you weren't) and therefore calorie burn was higher (it wasn't).

    RMR is higher than BMR merely because of the difference in tests.
    BMR you sleep in the lab, they wake you up, put a hood on you, and you could go back to sleep while they measure for 20 or more min.
    RMR you are awake, moved around already, and rested for 15-20 min but not supposed to sleep.

    That's why Katch BMR is:
    (21.6 x LBM in kg) + 370

    And even for that formula, more recent studies have shown that women are 2.5-5% below the result, and men 2.5-5% above, because of the difference in the metabolic organ size that cause most of the burn.

    The BodyMedia starts with a BMR based on gender, age, weight, height, and then adjusts based on nighttime heat over several days. But it can only adjust so much, because starting with that calculated BMR it think it knows about where it should be. And then how you sleep can foul that up too.
    So it may or may not be close.

    In BMF stats for the graph showing calorie burn through the day, find the lowest night-time lows of cal/min x 1440 for what it's using as BMR estimate.
    Close to Katch?

    Because that's pretty good it was close on the RMR part. That means the sensors seem to be working well for you for the simple stuff.
  • husseycd
    husseycd Posts: 814 Member
    Thanks! It's such a pain since all the estimates are so different, and I definitely don't want to be doing more damage by undereating. The scale finally dropped back down to 128 on Saturday. Unfortunately I had 3 good solid days with decent surpluses, so I expect to have maintained instead of dropped any more weight.

    In the end, I'm still going to move forward with my bulk. I guess I'll just watch the scale and make sure I'm not overeating and change accordingly. My RMR will either increase or it won't. I'll probably try to retest again in a few months just to see what it's doing.

    Still have the new BodPod test scheduled on Tuesday. Really curious to see what it says.