Exercise vs. RMR test

jeagogo

I did an RMR test (breathing through a tube for 10 minutes style) and worry that results might be off due to the 0.5 walk to the scanning facility from the subway station. It's the same walk I do twice a day to get to/from work, so it's by no means strenuous, but you are advised to avoid "working out" before the test. The result was that my RMR is apparently 400 calories higher than what would be formulaically calculated based on my age/sex/lean mass, so I'd like to investigate a bit before I start eating an extra 400 calories a day, y'know?

I've been Googling and can't find exactly what I'm looking for. Does anyone know of any studies that provide some information on how exercise immediately before an RMR test will impact results? Or care to weigh in based on your experience?

Stats, for reference:

Age/sex: 32, female
Height: 68"/ 173cm
Weight: 160 lbs/ 72.5 kg
Body fat (from DEXA scan): 28.4%

• RMR calculated from DEXA scan (so just using a formula based on sex/age/body fat %): 1,449 cal/day
• RMR test result (oxygen consumption test): 1,858 cal/day - this would mean that maintenance calories for me would be 2,229 cal/day.

I have a sedentary job, but do walk a bit everyday to/from work. I exercise 4+ times/week, however those calories burned are not added into RMR.

I've seen information about eating or consuming caffeine before the test that result in testing at a significantly higher RMR test result, but nothing about what percent of inflation can be seen in results based on activity. I've also read that menstrual cycle, especially the days before your period starts can increase RMR, thought I don't know by how much. That would be a valid factor in my test, though since many studies around RMR don't bother to control for menstrual cycles I imagine it's not too major a factor (or researchers are just lazy)?

cmriverside

Sounds like you've done plenty of research.

For the record, my calorie intake for someone my size, gender, age and activity level is about 500 calories above what any of the calculators tell me I should be eating to maintain my current weight.

If you are doing all this to try to pin down a calorie level at which to lose weight, I'd say just start logging your food. If you want to lose weight, learn how to log accurately. https://community.myfitnesspal.com/en/discussion/1234699/logging-accurately-step-by-step-guide/p1

Then track your exercise and food for 4-6 weeks, and adjust at the end of that time.

https://community.myfitnesspal.com/en/discussion/1080242/a-guide-to-get-you-started-on-your-path-to-sexypants/p1


It's an experiment we all have to run, and no one can give you exact numbers on really any of this, it's up to you to collect your data.

cmriverside

Also, for weight loss, you don't want to eat at your RMR, but at a deficit from your TDEE, so knowing an approximate RMR isn't really at all helpful. TDEE is calculated on the activity you do during your normal day, combined with how much purposeful exercise you get, then you subtract a percentage off your TDEE to create a calorie deficit. Myfitnesspal uses a slightly different algorithm, based on the Mifflin St Jeor calculation.

https://support.myfitnesspal.com/hc/en-us/articles/360032625391-How-does-MyFitnessPal-calculate-my-initial-goals-

Why not try 1700-1800 for a month or so and see how it goes? It's reasonable, and is likely close to what MFP would give you for, "Lose 1 pound per week," or, "Lose 1/2 pound per week." You're close to a healthy weight already, so you don't want to cut calories too much. Personally I would use, "Lose 1/2 pound per week."

NovusDies

That is the problem with RMR tests. The conditions under which they are performed are not tightly controlled. Your best option is to pick a number and run with it for 6 weeks and then evaluate the results. If you log your food accurately (I suggest using a food scale) you should get a fairly accurate idea of your tdee.

jeagogo

Fair points, thanks! I was hoping for something more accurate than just a formula with this test, but I suppose there is no avoiding the good ol' trial and error method.

PAV8888

400 Cal variance on TDEE, very plausible.

400 Cal variance on RMR? Seems a bit extreme. Remember RMR gets multiplied by your activity factor.

Do you have some reason to believe your resting rate is so much higher than average?

If I had such an outlying number I would try to repeat the test to verify the number, or use some other means to evaluate if it makes sense.